Electrode piezoelectric devices including surface wave devices

Claim 1

An acoustic surface wave device comprising a plate of piezoelectric material having one surface bearing first and second aluminum film interdigital electrodes containing 0.07 to 0.15% by weight of silicon or germanium and contained in a protective housing wherein the surfaces of the electrodes not in contact with the piezoelectric body bear a layer of amorphous aluminum oxide at least 100 Å thick formed by a process of heating the body bearing the aluminum electrodes at a temperature between 400° and 550 ° C. in an atmosphere containing free oxygen, and wherein the aluminum metal under the amorphous aluminum oxide layer is at least 400 Å thick.

Claim 5

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body with the aluminum containing from 0.07 to 0.15% by weight of Si or Ge which serve as an aluminum oxide crystallisation inhibitor, heating the body bearing the aluminum electrodes at a temperature between 400° and 550° C. in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 6

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body with the aluminum containing from 0.07 to 0.15% by weight of Si or Ge which serve as an aluminum oxide crystallisation inhibitor, heating the body bearing the aluminum electrodes at a temperature between 400° and 550° C. in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 7

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body wherein the aluminum of the electrodes contains less than 0.1% by weight by magnesium, heating the body bearing the aluminum electrodes at a temperature between 250° and 550° C. in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 8

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body wherein the aluminum of the electrodes contains less than 0.1% by weight by magnesium, heating the body bearing the aluminum electrodes at a temperature between 250° and 550° C. in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 9

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body by evaporating an aluminum-silicon alloy containing 0.5% by weight of silicon on the piezoelectric body, heating the body bearing the aluminum electrodes at a temperature of 450° C. for two minutes in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 10

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body by evaporating an aluminum-silicon alloy containing 0.5% by weight of silicon on the piezoelectric body, heating the body bearing the aluminum electrodes at a temperature of 450° C. for two minutes in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 11

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body, heating the body bearing the aluminum electrodes at a temperature between 350° and 450° C. for a period from 10 to 5 minutes in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.

Claim 12

A method of manufacturing a piezoelectric device comprising the steps of forming aluminum film electrodes on a piezoelectric body, heating the body bearing the aluminum electrodes at a temperature between 350° and 450° C. for a period from 10 to 5 minutes in an atmosphere containing free oxygen so as to form an amorphous aluminum oxide layer at least 100 Å thick on the surfaces of the electrodes not in contact with the piezoelectric body, and sealing the piezoelectric body bearing the electrodes in a protective housing, the initial thickness of the aluminum film electrodes being sufficient to leave a thickness of more than 400 Å of aluminum metal under the amorphous aluminum oxide layer.