KR101442426B1 - Strain gauge and method of manufacturing the same - Google Patents

Abstract

A strain gauge includes a substrate that is partitioned into a pad area and two or more gauge areas; a pad structure that is formed on the substrate corresponding to the pad area and is provided with a pad pattern portion; a gauge structure that is arranged on the substrate corresponding to the gauge area, is electrically connected to the pad structure, measures a resistance in accordance with a strain value, and is provided with gauge pattern portions separated from and electrically connected to each other; and a bridge structure where a first through-hole through the substrate is formed between the adjacent gauge pattern portions, a first bridge which connects the gauge pattern portion to each other being provided in the first through-hole.

Description

[0001] STRAIN GAUGE AND METHOD OF MANUFACTURING THE SAME [0002]

The present invention relates to a strain gauge and a method of manufacturing the same, and more particularly, to a strain gauge for measuring strain using a single crystal silicon substrate and a method for manufacturing the strain gauge.

Strain gauges are widely used for force and pressure measurements, structural stability monitoring, and biomechanical implants. The strain gauge may be classified into a metal thin type, a metal thin film type, a polycrystalline silicon type, and a monocrystalline silicon type.

Of these, monocrystalline silicon strain gages have been applied to ultra high pressure pressure sensors. However, when the monocrystalline silicon strain gauge is bonded to the diaphragm, the single crystal silicon strain gauge may be tilted to cause alignment problems. Further, when the single crystal silicon strain gauge is bonded to the diaphragm, a stable adherence is required. In addition, excellent strength is required for the single crystal silicon gauge.

It is an object of the present invention to provide a silicon gauge that can be stably attached to a diaphragm and can be bonded to an improved strength and precise position.

It is another object of the present invention to provide a method of manufacturing a silicon gauge that can be stably attached to a diaphragm and bonded to an improved strength and precise position.

According to an aspect of the present invention, there is provided a strain gauge including: a substrate divided into a pad region and at least two gauge regions, a pad formed on the substrate corresponding to the pad region, A gauge pattern disposed on the substrate corresponding to the gauge area and electrically connected to the pad structure to measure resistance according to a strain value and electrically connected to each other, A first through hole passing through the substrate is formed between the structure and adjacent gauge pattern portions, and the first through hole is formed with a bridge structure including a first bridge interconnecting the gauge pattern portions.

In one embodiment of the present invention, the gauge pattern portions extend in a first direction, and the gauge structure interconnects the respective end portions of adjacent gauge pattern portions and is arranged in a second direction perpendicular to the first direction And may further include an extended gauge connection. Here, the gauge connection part may be made of metal.

In addition, the gauge connection portion may have a cross-sectional shape of 'D'.

In an embodiment of the present invention, the gauge structure may have a meander structure in a plan view.

In one embodiment of the present invention, a second through hole is formed through the substrate between the gage structure and the pad structure, and the bridge structure is formed in the second through hole, and the gage structure and the pad structure And a second bridge that connects between the first bridge and the second bridge.

In the method of manufacturing a strain gauge according to an embodiment of the present invention, a substrate partitioned by a pad region and at least two gage regions is prepared. A pad structure having a pad pattern portion on the substrate corresponding to the pad region is formed. The gauge structure is formed on the substrate corresponding to the gauge area and electrically connected to the pad structure to measure resistance according to a strain value and having mutually spaced gauge pattern parts. A first through hole is formed through the substrate. And a first bridge interconnecting the gauge patterns in the first through-hole.

In an embodiment of the present invention, the substrate may include a single crystal silicon substrate or an SOI substrate.

In the manufacturing method according to an embodiment of the present invention, a process of forming a protective film on the substrate through an oxidation process for oxidizing the upper portion of the substrate may be further performed. Here, the gauge structure may include a step of forming the gauge pattern portions through an ion implantation process of injecting impurities into the upper portion of the substrate through the protective film. The pad structure may include a step of forming an ion implantation pattern through an ion implantation process of injecting an impurity into the upper portion of the substrate through the protection layer.

In order to form the pad structure and the gauge structure, the passivation film is partially etched to expose the pad pattern portion and the gauge pattern portions, and then a metal pattern and a gauge And forming a connection portion, respectively.

In one embodiment of the present invention, a process of forming a second through hole between the gage structure and the pad structure and forming a second bridge connecting the gage structure and the pad structure to the second through hole Can be performed additionally.

When the strain gauge manufactured according to the above-described strain gauge and its manufacturing method is subjected to a bonding process of bonding the strain gauge to the object using a glass frit, the first bridge included in the bridge structure, Thereby improving the strength of the gage structure by interconnecting the patterns. Therefore, damage of the strain gauge can be suppressed by providing the gauge structure having improved strength in the bonding process.

On the other hand, when the first through hole is not formed between the gauge patterns, the bonding position of the strain gauge may be displaced by the buoyancy of the strain gauge during the bonding process, When the first through hole is formed, the buoyancy is reduced and the strain gauge can be bonded to the correct position. Furthermore, as the frit formed on the bottom of the strain gauge is raised by the capillary phenomenon through the first through hole, the displacement of the strain gauge can be suppressed.

Furthermore, since the bubbles generated during the bonding process can be easily removed through the first through-holes, the strain gauge bonded to the object can ensure stable durability. In addition, contamination of the pick-up head picking up the strain gauge from the substrate in the bonding process can be suppressed. As the strain gauge has an improved strength, damage to the strain gauge in the bonding process can be suppressed. Further, when the pick-up head picks up the strain gauge, a sufficient pickup space is formed on the outer periphery of the strain gauge so that the pick-up head can easily pick up the strain gauge, have.

1A is a perspective view illustrating a strain gauge according to an embodiment of the present invention.
1B is a plan view for explaining the substrate of FIG. 1A.
1C is a plan view for explaining the strain gauge of FIG. 1A.
FIG. 1D is a cross-sectional view illustrating the strain gauge of FIG. 1A.
FIGS. 2A to 7A are plan views illustrating a method of manufacturing a strain gauge according to embodiments of the present invention.
FIGS. 2B to 7B are cross-sectional views illustrating a method of manufacturing a strain gauge according to embodiments of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the accompanying drawings, the sizes and the quantities of objects are shown enlarged or reduced from the actual size for the sake of clarity of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "comprising" and the like are intended to specify that there is a stated feature, step, function, element, or combination thereof, Quot; or " an " or < / RTI > combinations thereof.

On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

<Strain gauge>

1A is a perspective view illustrating a strain gauge according to an embodiment of the present invention. 1B is a plan view for explaining the substrate of FIG. 1A. 1C is a plan view for explaining the strain gauge of FIG. 1A. FIG. 1D is a cross-sectional view illustrating the strain gauge of FIG. 1A.

1A to 1D, a strain gauge according to an embodiment of the present invention includes a substrate 110, a pad structure 120, a gauge structure 130, and a bridge structure 140.

The substrate 110 may be divided into a pad region 111 and at least two gage regions. The pad region 111 is formed with a pad structure 120, which will be described later, and a gage structure 130 may be formed in the gage region. The pad region 111 corresponds to a center portion of the substrate 110 and the gage regions 117 and 118 may correspond to right and left portions around the pad region 111. [

The pad region 111 may include a common pad region 112 in which a common pad is to be formed and individual pad regions 113 and 114 in which individual pads are to be formed. The common pad region 112 may have a T shape, and the individual pad regions 113 and 114 may be defined on both sides of the common pad region 112.

The gage areas 117 and 118 may be defined on both sides of the substrate 110 with the pad area 111 as a center.

The substrate 110 may be made of monocrystalline silicon. Alternatively, the substrate 110 may include a silicon on insulator (SOI) substrate 110, which is an insulation layer on the silicon layer. The substrate 110 may be doped with ions of a first impurity type. For example, the substrate 110 may be doped with an ion of a Group 5 element of the N type such as nitrogen, phosphorus, arsenic, antimony, or the like.

The pad structure 120 is formed in the pad region 111 of the substrate 110. The pad structure 120 is formed on the substrate 110. The pad structure 120 may be connected to the gauge structure 130 and an external power source to measure a resistance value change of the gauge structure 130 according to a strain value of the gauge structure 130.

The pad structure 120 includes a pad pattern portion. The pad pattern portion includes a common pad 122 and individual pads 123 and 124.

The common pad 122 is formed in the common pad 112 region. The common pad 122 may have a T-shape in plan view. In addition, the common pad 122 may include a vertically stacked structure including an ion implantation pattern 122a and a metal pad pattern 122b.

That is, the ion implantation pattern 122a may be doped with ions of a second impurity type opposite to the first impurity type. For example, when the substrate 110 is doped with ions of a Group 5 element, the ion implantation pattern 122a may be doped with ions of a Group III element such as boron.

The metal pad pattern 122b may be formed of a metal such as aluminum or gold.

The individual pads 123, 124 are formed in the individual pad areas 113, 114. The individual pads 123 and 124 may have a stripe shape in a plan view. The individual pads 123 and 124 may have the same structure as the common pad. That is, the individual pads 123 and 124 may have a stacked structure having vertically stacked ion implantation patterns and metal pad patterns.

The gauge structure 130 is formed in the gauge areas 117 and 118, respectively. The gauge structure 130 is disposed on top of the substrate 110. The gage structure 130 may be electrically connected to the pad structure 120 to measure a resistance value that varies depending on a strain value. Accordingly, the gage structure 130 may be electrically connected to the pad structure 120 to form a Wheatstone bridge circuit. As a result, when strain is generated on the object to which the strain gauge is attached, the resistance of the gauge structure 130 changes, so that the strain of the object can be measured.

The gauge structure 130 may include a plurality of gauge pattern portions 137 and gauge connection portions 138. The gauge pattern portion 137 extends in the first direction. The gauge pattern portion 137 extending in the first direction may include an end portion connected to the common pad 122 and the individual electrodes 123 and 124, respectively.

The gauge pattern portion 137 is formed on the substrate 110. The gauge pattern portion 137 has a stripe shape. The gauge pattern unit 137 may have a plurality of gauge patterns spaced from each other and extending in a first direction. The gauge pattern unit 137 may be formed on the substrate 110 through an ion implantation process of the second impurity type element.

The gauge connection portions 138 electrically connect the gauge pattern portions 137 by connecting ends of adjacent gauge patterns. Accordingly, the gage structure 130 and the pad structure 120 can be electrically connected to each other. Also, the gauge connection part 138 may extend in a second direction perpendicular to the first direction.

The gauge connection 138 may be made of metal such as aluminum and gold. Thus, the gauge connection portion 138 can prevent the gauge pattern portion 137 from contracting or expanding in the second direction, so that the gauge connection portion 138 can be selectively and uniformly contracted or expanded in the first direction .

Meanwhile, the gauge connection portion 138 may have a U-shaped cross-sectional shape.

In an embodiment of the present invention, the gage structure 130 may have a meander structure in plan view. That is, since the gauge pattern portion 137 is formed relatively long, the sensitivity of the strain gauge can be improved.

The bridge structure 140 includes a first bridge 141 formed in the first through hole 101. Here, the first through holes 101 are formed to penetrate the substrate 110 between adjacent gauge patterns. The first bridge 141 is formed in the first through hole 101, and the strength of the gauge pattern portion 137 can be compensated by connecting the gauge patterns.

That is, when a bonding process for bonding the strain gauge to a target object using glass frit is performed, the first bridge 141 included in the bridge structure 140 interconnects the gauge patterns Thereby improving the strength of the gage structure 130. Therefore, damage of the strain gauge can be suppressed by providing the gauge structure 130 having an improved strength in the bonding process.

On the other hand, if the first through hole 101 is not formed between the gage patterns, the bonding position of the strain gage may be displaced by the buoyancy of the strain gage during the bonding process, When the first through hole 101 is formed between the strain gauges, the buoyancy is reduced and the strain gauge can be bonded to the precise position of the object. Further, as the frit formed on the bottom of the strain gauge is raised by the capillary phenomenon through the first through hole 101, the displacement of the strain gauge can be suppressed.

Furthermore, since the bubbles generated during the bonding process can be easily removed through the first through-hole 101, the strain gauge bonded to the object can ensure stable durability.

In an embodiment of the present invention, a second through hole 102 may be formed between the gage structure 130 and the pad structure 120 to penetrate the substrate 110. The bridge structure 140 may further include a second bridge 142 formed in the second through hole 102.

The second bridge 142 interconnects the gage structure 130 and the pad structure 120. Thus, the second bridge 142 can improve the strength of the strain gage. Meanwhile, the second through-hole 102 can eliminate the misalignment of the position in the bonding process and further remove a path for removing bubbles.

The strain gage according to an embodiment of the present invention may further include a protective layer 150 on the substrate 110 between the gage patterns and between the common pad 122 and the individual pads 123 and 124 have.

The passivation layer 150 may prevent a short circuit between the gage patterns and a short circuit between the common pad 122 and the individual pads 123 and 124. That is, moisture during operation of the strain gauge may be attached between the gauge patterns to electrically connect between the gauge patterns, thereby causing malfunction of the strain gauge. Therefore, the protective film is formed between the gauge patterns, so that malfunction of the strain gauge can be suppressed.

&Lt; Method of producing strain gauge >

FIGS. 2A to 7A are plan views illustrating a method of manufacturing a strain gauge according to embodiments of the present invention. FIGS. 2B to 7B are cross-sectional views illustrating a method of manufacturing a strain gauge according to embodiments of the present invention.

Referring to FIGS. 2A and 2B, first, a substrate 110 is prepared. The substrate 110 may be made of monocrystalline silicon. Alternatively, the substrate 110 may include a silicon on insulator (SOI) substrate 110, which is an insulation layer on the silicon layer. In addition, the substrate 110 may be doped with ions of a first impurity type. For example, the substrate 110 may be doped with an ion of a Group 5 element of the N type such as nitrogen, phosphorus, arsenic, antimony, or the like.

The substrate 110 may be divided into a pad region 111 and at least two gage regions. The pad region 111 is formed with a pad structure 120, which will be described later, and a gage structure 130 may be formed in the gage region. The pad region 111 corresponds to a central portion of the substrate 110, and the gage region may correspond to right and left portions around the pad region 111.

The pad region 111 may include a common pad region in which a common pad is to be formed and individual pad regions in which individual pads are to be formed. The common pad region may have a T shape, and the individual pad regions may be defined on both sides of the common pad region.

The gage areas 117 and 118 may be defined on both sides of the substrate 110 with the pad area 111 as a center.

Referring to FIGS. 3A and 3B, a protective layer 150 may be formed on the substrate 110. The protective layer 150 may be formed by oxidizing the upper surface of the substrate 110, for example. At this time, the passivation layer 150 may be formed of silicon oxide. In order to form the protective film, a wet or dry oxidation process may be performed. The protective layer 150 may function as a buffer in a subsequent ion implantation process. The protective film 150 may protect the strain gage.

4A and 4B, after the protective layer 150 is formed, the ion implantation patterns 122a, 123a, 124a and the gauge pattern portion 137 included in the pad structure 120 are ion- .

According to the ion implantation process, the ion implantation pattern 122a, 123a, 124a and the gauge pattern portion 137 are formed by doping an element of the second impurity type opposite to the first impurity type on the lower portion of the protective film 150 can do. That is, when the first impurity type corresponds to a Group 5 element, the second impurity type may correspond to a Group III element such as boron.

Also, in the ion implantation step, the impurity of the second impurity type may be doped at a concentration of 1.0 10 ¹⁶ ions / cm 2 to 5.0 10 ¹⁶ ions / cm 2. At this time, the ion implantation angle can be adjusted to 5 to 20..

Here, the ion implantation patterns 122a, 123a, and 124a may correspond to components forming the common pad 122 and the individual pads 123 and 124, and the gage pattern portion 137 may be formed in the gage structure 130).

The gage pattern portion 137 may have a plurality of gauge patterns having the stripe shape extending in the first direction and spaced apart from each other. In addition, the ion implantation patterns 122a, 123a and 124a may include a T-shaped pattern for forming a common pad and a stripe pattern extending in a second direction perpendicular to the first direction for forming individual pads .

Meanwhile, after the ion implantation process, the ion implantation patterns 122a, 123a, and 124a and the gauge pattern portion 137 may be further annealed in a hydrogen atmosphere.

Referring to FIGS. 5A and 5B, the first recesses 151, 152, and 153 for partially etching the passivation layer 150 to expose the ion implantation patterns 122a, 123a, and 124a, Thereby forming a second recess 154 exposing each end. A metal pattern may be formed on the first recesses 151, 152, and 153 and a gage connection portion 138 may be formed on the second recesses 154 to interconnect the gage patterns.

Electrical separation between the gauge patterns can be achieved through the etching process. As a result, the influence of moisture or the like between the gauge patterns can be suppressed.

Meanwhile, a wet etching process or a dry etching process may be performed to partially etch the passivation layer 150.

6A and 6B, metal patterns 122b, 123b and 124b are formed on the ion implantation patterns 122a, 123a and 124a exposed by the first recesses 151, 152 and 153, . And a gauge connection portion 138 connecting each end of the gauge patterns exposed by the second recesses 154 is formed.

The metal patterns 122b, 123b, and 124b and the gauge connection portion 138 may be formed through a sputtering process or a vacuum deposition process. The metal patterns 122b, 123b, and 124b and the gauge connection portion 138 may be formed using a metal material such as aluminum or gold.

In an embodiment of the present invention, a preliminary metal layer (not shown) such as chromium or titanium may be formed before forming the metal patterns 122b, 123b, and 124b and the gage connection portion 138. [ The preliminary metal layer can improve the adhesion of the metal pattern.

Further, the metal patterns 122b, 123b, and 124b and the gage connection portion 138 may be further subjected to an annealing process.

7A and 7B, a first through hole 101 penetrating the substrate 110 is formed between the gage patterns by partially removing the protective film 150, and the first through hole 101 The first bridge 141 interconnecting the gauge patterns is formed. A second through hole 102 passing through the substrate 110 is formed between the gage structure 130 and the pad structure 120 and the gage structure 130 is formed in the second through hole 102. [ And the second bridge 142 connecting the pad structure 120 may be additionally formed.

An etch process may be performed to partially remove the passivation layer 150. The etching process may completely penetrate the substrate and contribute to the enhancement of adhesion of the glass frit in a subsequent bonding process.

According to the strain gauge according to the embodiments of the present invention, when a bonding process of bonding the strain gauge to the object using glass frit is performed, the first strain gauge included in the bridge structure 140 The bridge improves the strength for the gage structure 130 by interconnecting the gage patterns. Therefore, damage of the strain gauge can be suppressed by providing the gauge structure 130 having an improved strength in the bonding process.

On the other hand, when the first through hole is not formed between the gauge patterns, the bonding position of the strain gauge may be displaced by the buoyancy of the strain gauge during the bonding process, When the first through hole is formed, the buoyancy is reduced and the strain gauge can be bonded to the correct position. Furthermore, as the frit formed on the bottom of the strain gauge is raised by the capillary phenomenon through the first through hole, the displacement of the strain gauge can be suppressed.

Furthermore, since the bubbles generated during the bonding process can be easily removed through the first through-holes, the strain gauge bonded to the object can ensure stable durability.

The strain gauge described above and the technique according to the manufacturing method of the strain gauge can be applied to various high pressure sensors such as automobiles, airplanes, ships, and household appliances.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It can be understood that it is possible.

Claims (13)

A substrate partitioned by a pad region and at least two gauge regions;
A pad structure formed on the substrate corresponding to the pad region, the pad structure including a pad pattern portion;
A gauge structure disposed on the substrate corresponding to the gauge region, the gauge structure electrically connected to the pad structure to measure resistance according to a strain value, and gauge pattern portions mutually spaced and electrically connected; And
A first through hole passing through the substrate is formed between the adjacent gauge pattern portions and a first bridge connecting the gauge pattern portions to the first through hole is provided. Strain gauge. The apparatus of claim 1, wherein the gauge pattern portions extend in a first direction,
Wherein the gage structure further comprises gauge connection portions interconnecting respective ends of adjacent gauge pattern portions and extending in a second direction perpendicular to the first direction. 3. The strain gauge of claim 2, wherein the gauge connection is made of metal. 3. The strain gauge of claim 2, wherein the gauge connection portion has a &quot; D &quot; The strain gauge of claim 1, wherein the gauge structure has a meander structure in a planar manner. [2] The apparatus of claim 1, wherein a second through hole is formed between the gage structure and the pad structure,
Wherein the bridge structure further comprises a second bridge formed in the second through hole and connecting between the gage structure and the pad structure. Preparing a substrate partitioned by a pad region and at least two gauge regions;
Forming a pad structure having a pad pattern portion on the substrate corresponding to the pad region;
Forming a gauge structure on the substrate corresponding to the gauge region, the gauge structure being electrically connected to the pad structure, measuring a resistance according to a strain value, and having gauge pattern portions spaced apart from each other;
Forming a first through hole between the gauge pattern portions adjacent to each other through the substrate; And
And forming a bridge structure having a first bridge interconnecting the gauge patterns to the first through-hole. 8. The method of claim 7, wherein the substrate comprises a single crystal silicon substrate or an SOI substrate. 8. The method of claim 7, further comprising forming a protective film on the substrate through an oxidation process for oxidizing the upper portion of the substrate. The method as claimed in claim 9, wherein the forming of the gauge structure comprises forming the gauge pattern units through an ion implantation process of injecting impurities into the upper portion of the substrate through the protective film. 10. The method of claim 9, wherein forming the pad structure includes forming an ion implantation pattern through an ion implantation process of implanting impurities into the upper portion of the substrate through the protection film. Way. 10. The method of claim 9, wherein forming the pad structure and the gauge structure comprises:
Partially exposing the protective film to expose the pad pattern portion and the gauge pattern portions; And
And forming a metal pattern and a gauge connection portion on the pad pattern portion and the gauge pattern portions, respectively. 8. The method of claim 7, further comprising: forming a second through hole between the gage structure and the pad structure;
And forming a second bridge between the gage structure and the pad structure in the second through hole. &Lt; Desc / Clms Page number 19 &gt;

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