Microtransformer for system-on-chip power supply

• US 20050105225A1
• Filed: 12/03/2004
• Published: 05/19/2005
• Est. Priority Date: 08/06/2003
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Ahn, Kie Y., Forbes, Leonard
• Granted Patent: US 6,992,871 B2
• Time in Patent Office: Days
• US Class Current: 361/18
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 41/046 structurally combined with ferromagnetic material
• CPC Class Codes: H01L 2224/05571 the external layer being disposed in a recess of the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 23/147 Semiconductor insulating substrates semiconductor conductive substrates H01L23/4926
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 23/50 for integrated circuit devices, e.g. power bus, number of leadsH01L23/482 - H01L23/498 take precedence
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 23/645 Inductive arrangements H01L23/647, H01L23/66 take precedence
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/19103 interposed between the semiconductor or solid-state device and the die mounting substrate, i.e. chip-on-passive

Abstract

A microtransformer for a high-performance system-on-chip power supply is disclosed. Through-wafer openings in a substrate allow the primary and secondary wiring on both surfaces of the silicon substrate. An insulating silicon oxide layer is first deposited on all surfaces of the substrate. A magnetic film is further deposited on the silicon oxide layer followed by the application of another insulating layer. Coils are fabricated next by patterned deposition on both sides of the substrate and through the holes. The coils can be, e.g., single coils or primary or secondary coils of a transformer structure, with secondary having one or more output taps to supply different output voltages. For better flux closure, various magnetic layers and insulators can be deposited on top of the windings.

Claims

1-104. -104. (canceled)

105. A method for fabricating a microtransformer, the method comprising the steps of:

providing a substrate with at least a first and second through-holes that define between them a coil winding area that includes a top surface of said substrate, a bottom surface of said substrate, and side surfaces of said through-holes;

forming a thermal oxide layer over said substrate;

forming a layer of magnetic material over said thermal oxide layer;

forming a copper layer over said layer of magnetic material;

patterning said copper layer to form a plurality of copper coils; and

forming a top protective layer over said plurality of copper coils.

106. The method of claim 105, wherein said thermal oxide layer comprises silicon oxide.

107. The method of claim 105, wherein said layer of magnetic material comprises a plurality of magnetic films laminated with insulating spacers.

108. The method of claim 105, wherein said plurality of copper coils are formed to a thickness of about 10 micrometers.

109. The method of claim 105, wherein said copper layer is formed by electroplating.

110. The method of claim 105 further comprising the step of providing a first insulating layer between said layer of magnetic material and said copper layer.

111. The method of claim 110 further comprising the step of providing a second insulating layer between said plurality of copper coils and said top protective layer.

112. The method of claim 111 further comprising the steps of:

forming a second layer of magnetic material over said plurality of copper coils;

forming a third insulating layer over said second layer of magnetic material;

forming a layer of conductive material over said third insulating layer; and

patterning said layer of conductive material to form a plurality of conductive coils.

113. The method of claim 112 further comprising the step of providing a passivating layer over said plurality of conductive coils.

115. The method of claim 112, wherein said masking layer is formed of a thermally grown oxide.

116. The method of claim 112, wherein etching of said silicon substrate is conducted with an aqueous etching solution.

117. The method of claim 112, wherein said step of providing a transformer core on said silicon substrate and within said coil winding region further comprises the steps of:

forming a polyimide layer over said silicon substrate;

forming a layer of magnetic material over said polyimide layer;

forming an electrically conductive layer over said layer of magnetic material;

patterning said electrically conductive layer to form a plurality of coils; and

forming a top protective layer over said plurality of coils.

114. A method of forming a coil winding region of a microtransformer, the method comprising the steps of:

providing a silicon substrate;

providing a masking layer having at least a first and second openings over said silicon substrate;

etching said silicon substrate by employing said masking layer to form at least a first and second through-holes, the first and second through-holes defining between them a coil winding region; and

providing a transformer core on said silicon substrate and within said coil winding region.

118. An integrated circuit microtransformer comprising:

a substrate with at least a first and second through-holes that define between them a coil winding region, said first and second through-holes each having a width of about 1 millimeter; and

a transformer core provided on said substrate and within said first and second through-holes, said transformer core comprising less than or equal to 83 coil windings.

119. The microtransformer of claim 118, wherein said coil windings comprise a conductive material.

120. The microtransformer of claim 118, wherein said conductive material is selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, silver and silver alloys.

121. The microtransformer of claim 118, wherein said transformer core further comprises a magnetic material between said substrate and said coil windings.

122. The microtransformer of claim 121, wherein said magnetic material magnetic material is made of Fe—

X—

N alloy or Fe—

X—

B—

N alloy, wherein X is at least one atom selected from the group consisting of Zr, Hf, Ti, Nb, Ta, V, Mo, W, and Cr.

123. The microtransformer of claim 121, wherein said magnetic material is further formed of a plurality of thin soft magnetic layers and at least one insulating spacer layer formed between said thin soft magnetic layers.

124. The microtransformer of claim 123, wherein said insulating spacer layer is formed of a material selected form the group consisting of Permalloy (NiFe), NiFeMo, Co—

Zr, CoZrRe, CoFeSiB, CoNbZr, and Co—

Cr—

O granular films.