JP2004264253A - Metal wire support structure and stopper of semiconductor acceleration sensor having the structure. - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form at a low cost by utilizing a regular wire bonding device. <P>SOLUTION: This stopper 2 of a semiconductor acceleration sensor 1 is provided on the semiconductor acceleration sensor 1 formed by providing in rows a substrate 3a and a weight body 3c supported relatively displaceably to the substrate 3a on the chip face of a semiconductor chip 3, and prevents excessive relative displacement of the weight body 3c to the substrate 3a. The stopper 2 is equipped with a gold wire 5 disposed so that a length direction middle portion passes over the weight body 3c, for preventing relative displacement over a prescribed limit of the weight body 3c, and a support part 6 for supporting portions to be supported which are both end sides of the length direction middle portion respectively on prescribed spots on the substrate 3a. The support part 6 is equipped with a pair of support bumps formed on both sides of a gold wire center shaft at the portions to be supported, and the portions to be supported are disposed on recessed parts formed between both support bumps 10. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal wire support structure for supporting a metal wire on a semiconductor chip or a circuit board, and a stopper for a semiconductor acceleration sensor having the structure.
[0002]
Problems to be solved by the prior art and the invention
First, a conventional metal wire supporting method will be described. FIG. 13 illustrates a wire loop 90 formed when a gold wire is supported on a semiconductor chip or a circuit board by a conventional wire bonding method (for example, see Patent Document 1). This wire loop 90 has the following features.
(1) The used gold wire is thin (25 to 30 μm in diameter).
(2) Since gold is soft, various shapes can be formed (see FIGS. 13A to 13D).
(3) The loop height h1 can be controlled.
[0003]
However, the conventional wire bonding method has the following problems.
(1) Since the gold is soft, the shape of the wire loop 90 is easily deformed. For this reason, when a plurality of wire loops 90 are provided close to each other, or when the wire loops 90 are three-dimensionally crossed, for example, the wire loops 90 may be deformed and short-circuited.
(2) It was very difficult to control the loop height h1 to about 100 μm or less. If the thickness is about 100 μm or less, there is a problem that a crack is generated at the loop rising portion of the gold wire and the wire is easily broken.
[0004]
Next, the stopper of the conventional semiconductor acceleration sensor will be described. A semiconductor acceleration sensor using a piezoresistive effect of a semiconductor has a weight formed by etching a part of a semiconductor substrate and a beam for supporting the weight at the same time as disclosed in Patent Document 2, for example. It is configured to detect the applied acceleration by detecting the three-dimensional displacement of the weight and the beam. With this semiconductor acceleration sensor, it is necessary to form the beam thinly in order to be able to detect a very small acceleration, but when doing so, the deflection of the beam when excessive acceleration is applied increases, and the beam exceeds its elastic limit. It will be damaged. For this reason, a stopper is provided to prevent excessive bending of the beam. The stopper must be configured so as to have a space that allows deflection of the beam below a predetermined limit. For example, (a) a space is formed by etching glass, or (b) a resist is formed on the surface of glass. It is configured to form a film pattern and relatively form a space in a portion where a resist film is not formed.
[0005]
However, in order to manufacture a conventional stopper, for example, the method of (b), which is said to be a simple method with fewer steps than the method of (a), requires the following three steps. Is required.
(1) A resist is applied on a stopper substrate using glass, and is rotated at a predetermined rotation number for a predetermined time to form a resist film (resist coating step).
(2) A desired pattern is formed by exposing the resist film formed in (1) using a desired pattern at a predetermined exposure amount and developing the resist film (resist pattern forming step).
(3) The pattern formed in (2) is baked at a predetermined temperature for a predetermined time, the resist is formed as a structure, and a stopper is formed (baking step).
[0006]
As described above, the conventional stopper has a problem in that the manufacturing thereof requires a multi-step process and is costly.
[0007]
[Patent Document 1]
JP-A-11-307571 [Patent Document 2]
JP-A-8-107218
An object of the present invention is to provide a metal wire supporting structure that solves the above-mentioned problem and a stopper for a semiconductor acceleration sensor having the structure.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a metal wire support structure of the present invention is a metal wire support structure that supports a supported portion, which is a midpoint in the length direction of a metal wire, at a predetermined point on a semiconductor chip or a circuit board, A pair of bumps are formed on both sides of the central axis of the metal wire in the supported portion, and the supported portion is disposed in a concave portion formed between the bumps.
[0010]
Further, the metal wire support structure of the present invention is a metal wire support structure for supporting a supported portion, which is an intermediate portion in the length direction of a metal wire, at a predetermined point of a semiconductor chip or a circuit board, and is formed at the predetermined point. A groove-shaped recess extending in the length direction of the central axis of the metal wire at the supported portion is formed on the upper surface of the pad, and the supported portion is disposed in the recess. ing.
[0011]
In the metal wire support structure, an embodiment is provided in which a bump formed so as to press the supported portion from above the concave portion is provided.
[0012]
Further, the stopper of the semiconductor acceleration sensor of the present invention is provided in a semiconductor acceleration sensor in which a base and a weight supported so as to be relatively displaceable with respect to the base are arranged on a chip surface of a semiconductor chip, A stopper for preventing an excessive relative displacement of the weight body with respect to the base body, wherein a part in the longitudinal direction is disposed so as to pass above the weight body, and a predetermined limit of the weight body is provided. A metal wire for preventing the above relative displacement, and a supporting portion for supporting the supported portions at both ends of the longitudinally intermediate portion at predetermined points on the base, at least one of the supporting portions, A pair of bumps are formed on both sides of the central axis of the metal wire in the supported portion, and the supported portion is disposed in a concave portion formed between the bumps.
[0013]
Further, the stopper of the semiconductor acceleration sensor of the present invention is provided in a semiconductor acceleration sensor in which a base and a weight supported so as to be relatively displaceable with respect to the base are arranged on a chip surface of a semiconductor chip, A stopper for preventing an excessive relative displacement of the weight body with respect to the base body, wherein a part in the longitudinal direction is disposed so as to pass above the weight body, and a predetermined limit of the weight body is provided. A metal wire for preventing the above relative displacement, and a supporting portion for supporting the supported portions at both ends of the longitudinally intermediate portion at predetermined points on the base, at least one of the supporting portions, A pad formed at a predetermined point on the base; a groove-shaped recess extending in the length direction of the central axis of the metal wire at the supported portion is formed on an upper surface of the pad; There is no supported part To have.
[0014]
In the stopper of the semiconductor acceleration sensor, an example is provided in which the support portion includes a bump formed so as to press the supported portion from above the concave portion.
[0015]
In the above, although the bump is not particularly limited, a minute ball is formed at the tip of the metal wire by using discharge or hydrogen flame, and after the minute ball is pressed against a semiconductor chip or a circuit board, the metal wire is An example formed by cutting from the neck portion of a ball is shown.
[0016]
The pad is not particularly limited, but a pad formed by etching on the surface of the semiconductor chip or the circuit board is exemplified.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 6 show a first embodiment of the present invention. Hereinafter, an embodiment in which the present invention is embodied in the stopper 2 of the semiconductor acceleration sensor 1 will be described with reference to the drawings together with the metal wire support structure of the stopper 2.
[0018]
As shown in FIG. 1, the semiconductor acceleration sensor 1 is supported by a rectangular frame-shaped base 3a and four beams 3b in the frame of the base 3a, so that the semiconductor acceleration sensor 1 can be displaced relative to the base 3a. The supported weight 3c is arranged in a row on the chip surface of the semiconductor chip 3. The four beams 3b are arranged in a cross shape extending in the X-axis direction and the Y-axis direction. The beam 3b in the X-axis direction is provided with four piezo elements 4x for detecting the X-axis direction and four piezoresistive elements 4z for detecting the Z-axis direction, and the beam 3b in the Y-axis direction is provided with a piezo element for detecting the Y-axis direction. Four resistance elements 4y are provided. The weight body 3c is formed in a four-leaf clover shape in a plan view, and the center part thereof is connected to the tip part of each beam 3b. In the semiconductor acceleration sensor 1, when the weight 3c receives acceleration, the beam 3b is deformed, and the change in the resistance value of the piezoresistive elements 4x, 4y, 4z disposed on the surface is detected. The acceleration is detected.
[0019]
The stopper 2 is for preventing an excessive relative displacement of the weight body 3c in a predetermined direction (Z direction in this example) with respect to the base body 3a. As shown in FIG. A gold wire 5 disposed so as to pass above the weight body 3c and preventing relative displacement of the weight body 3c beyond a predetermined limit; and a supported part 5a at both ends of the middle part in the length direction. And a support portion 6 for supporting each at a predetermined point on the base 3a. Then, when an excessive acceleration in the Z direction is applied to the weight body 3c, the stopper 2 suppresses the displacement of the weight body 3c in the Z direction by a predetermined amount or more with respect to the base 3a. As the stopper 2, although not particularly limited, a case where a gold wire 5 having a diameter of about 25 μm is used, a loop height h1 is set to about 100 μm, and a support height h2 of the gold wire 5 to the base 3a is set to about 50 μm is exemplified. (See FIG. 2 (b)). The supporting height h2 of the gold wire is appropriately set according to the specifications of the semiconductor acceleration sensor 1.
[0020]
The gold wire 5 is disposed so as to linearly connect a first bonding point P1 and a second bonding point P2 which are set at both ends of a straight line connecting the pair of predetermined points with a space therebetween in a plan view. ing. In this example, the bump 13 is formed in advance at the second bonding point P2, and then the gold wire 5 is bonded in the order of the first bonding point P1 and the second bonding point P2.
[0021]
As shown in FIG. 3, the support portion 6 includes a pair of support bumps 10 formed on both sides of the central axis of the gold wire in the supported portion 5a, and the support portion 6 is supported by a concave portion 11 formed between the support bumps 10. The part 5a is provided. Further, the support portion 6 includes a pressing bump 12 formed so as to press the gold wire 5 from above the concave portion 11.
[0022]
Next, a method for forming the stopper 2 (metal wire supporting method) according to the present invention using a wire bonding apparatus will be described with reference to FIGS. The wire bonding apparatus used in this example has a capillary 7 having a through hole formed at the center thereof for passing the gold wire 5 and pressing the gold wire 5 protruding forward from the through hole toward a bonding point at a tip end thereof; A wire clamper 9 for clamping and releasing the gold wire 5 above the wire 7 and a drive mechanism (not shown) for moving the capillary 7 and the wire clamper 9 horizontally and vertically.
[0023]
(1) Four support bumps 10 are formed on the semiconductor chip 3 (FIG. 4A). This is a step of forming a pair of support bumps 10 on both sides of the center axis of the gold wire in the supported portion 5a. At the same time, the bump 13 at the second bonding point P2 is formed. Each of the bumps 10 and 13 is formed as follows, similarly to the bumps formed by the known ball bonding method.
(1-1) At the tip of the gold wire 5 penetrating the capillary 7, a minute gold ball 8 is formed by using discharge or hydrogen flame (FIG. 5A).
(1-2) The micro gold ball 8 is pressed down on the semiconductor chip 3 by descending the capillary 7 to form a bump (FIG. 5B). Here, since the minute gold ball 8 formed at the tip of the gold wire 5 is formed by melting and then recrystallizing, the ball neck has a partially brittle property.
(1-3) After slightly raising the capillary 7 (FIG. 5 (c)), the gold wire 5 is clamped by the wire clamper 9, and the capillary 7 and the wire clamper 9 are raised as they are, and the gold wire 5 is finely gold-plated. The ball 8 is cut from the neck to form the support bump 10 or the bump 13 (FIG. 5D).
[0024]
(2) The gold wire 5 is disposed between the first bonding point P1 and the second bonding point P2 as follows (FIG. 4B). This is a stage in which the supported portion 5a is provided in the concave portion 11 formed between the two support bumps 10 in each support portion 6.
(2-1) The first bonding 15 is formed at the first bonding point P1 in the same manner as (1-1) to (1-2) (FIG. 6A).
(2-2) By moving the capillary 7 so as to draw a semicircle in the direction of the second bonding point P2 (FIG. 6B), the gold wire 5 is distributed to the vicinity of the support portion 6 on the first bonding point P1 side. Set up. Further, by moving the capillary 7 linearly in the direction of the second bonding point P2 (FIG. 6C), the gold wire 5 is disposed so as to pass through the recess 11 of each support portion 6.
(2-3) The gold wire 5 is pressed against the bump 13 at the second bonding point P2 to form the second bonding 16. At this time, the gold wire 5 is cracked by the tip of the capillary 7 to crush the gold wire 5.
(2-4) After slightly raising the capillary 7, the gold wire 5 is clamped by the wire clamper 9, the capillary 7 and the wire clamper 9 are raised as it is, and the gold wire 5 is cut from a cracked portion. (FIG. 6 (d)).
[0025]
(3) Pressing bumps 12 are formed so as to press down the gold wires 5 from above the recesses 11 (FIG. 4C). This pressing bump 12 is formed in the same manner as in the above (1). Thus, the stopper 2 is completed.
[0026]
According to the stopper 2 of the present invention configured as described above, the middle part in the length direction is disposed so as to pass above the weight 3c, and the relative displacement of the weight 3c that is equal to or greater than a predetermined limit is provided. And a supporting portion 6 for supporting the supported portions 5a at both ends of the middle portion in the longitudinal direction at predetermined points on the base 3a. At least one of the supporting portions 6 is Since a pair of support bumps 10 are formed on both sides of the center axis of the gold wire in the support portion 5a, and the supported portion 5a is disposed in the concave portion 11 formed between the two support bumps 10, It can be formed using a known wire bonding apparatus used for extracting a signal from the semiconductor chip 3. Therefore, unlike the conventional example requiring many steps, it can be formed at low cost.
[0027]
Further, according to the metal wire supporting structure of the present invention, a pair of supporting bumps 10 formed on both sides of the central axis of the gold wire in the supported portion 5a is provided. Since the supported portion 5a is provided, the gold wire 5 can be supported at a predetermined height h2 at a predetermined position of the semiconductor chip 3. The predetermined height h2 at this time is determined by the size and shape of the support bump 10, and the support bump 10 can be supported at a height that is almost impossible to realize conventionally.
[0028]
In addition, since the supporting portion 6 and the gold wire supporting structure in the stopper 2 of the present invention include the pressing bumps 12 formed so as to press the supported portion 5a from above the concave portion 11, the gold wire 5 is placed at a predetermined position. It can be securely held. And in the stopper 2, an excessive relative displacement of the weight body 3c in the Z direction can be reliably prevented.
[0029]
Next, FIG. 7 shows a stopper 30 of a semiconductor acceleration sensor according to a second embodiment of the present invention, and a metal wire support structure of the stopper 30. This embodiment differs from the first embodiment only in the following points. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will not be repeated (the same applies to the following embodiments).
[0030]
The stopper 30 of the present embodiment uses one of the support portions 6 (the right side in FIG. 7) of the first embodiment, and uses the bump 13 formed at the second bonding point P2 as the support portion. Therefore, the method of forming the stopper 30 (the method of supporting the metal wire) omits the procedure of forming the one support portion 6 in the first embodiment, and further description will be omitted. According to this embodiment, the same effect as that of the first embodiment can be obtained.
[0031]
Next, FIGS. 8 to 10 show a stopper 40 of a semiconductor acceleration sensor according to a third embodiment of the present invention, and a supporting structure of the metal wire of the stopper 40. This embodiment differs from the first embodiment only in the following points.
[0032]
That is, the support portion 41 of the stopper 40 of the present embodiment includes a pad 42 formed at a predetermined point on the base 3a, as shown in FIGS. , A groove-shaped recess 43 extending in the length direction of the central axis of the gold wire is formed, and the supported portion 5a is provided in the recess 43.
[0033]
The method of forming the stopper 40 (metal wire supporting method) includes forming the pad 42 at the predetermined point by, for example, etching, and extending the gold wire central axis in the supported portion 5 a on the upper surface of the pad 42. The method includes a step of processing the groove-shaped concave portion 43 with a blade-shaped capillary 44 (see FIG. 10), and a step of disposing the supported portion 5a in the concave portion 43.
[0034]
According to this embodiment, the same effect as that of the first embodiment can be obtained.
[0035]
Next, FIG. 11 shows a fourth embodiment of the invention. This embodiment shows a fence 50 having a metal wire support structure according to the present invention.
[0036]
This fence is for preventing mold flow and resin flow on the circuit board, and is composed of two parallel fence bodies 51 having the same structure as the stopper 2 in the first embodiment. Therefore, it can be formed similarly to the stopper 2. The two fences 51 are disposed so that their length directions are inverted from each other, so that one of the loop portions 51a (the portion raised from the surface of the semiconductor chip 3 or the circuit board) is connected to the other horizontal portion. 51b (a portion disposed near the surface of the semiconductor chip 3 or the circuit board) covers each other, and prevents a mold flow or a resin flow over the entire length of the fence 50.
[0037]
According to this embodiment, similarly to the first embodiment, a well-known wire bonding apparatus used for extracting a signal is used to reduce the cost of the fence 50 for preventing the mold flow and the resin flow on the circuit board at low cost. Can be formed.
[0038]
Next, FIG. 12 shows a fifth embodiment that embodies the present invention. This embodiment shows a three-dimensional intersection 60 of the gold wire 5 having the metal wire support structure according to the present invention.
[0039]
The three-dimensional intersection 60 is obtained by arranging two connecting bodies 61 having the same structure as the stopper 2 in the first embodiment in an intersecting manner. Therefore, it can be formed similarly to the stopper. In this three-dimensional intersection 60, the loop portion 61a of one connecting body 61 is disposed so as to straddle the horizontal portion 61b of the other connecting body 61. Thus, for example, by setting the loop height h1 within 150 μm, several gold wires 5 can be crossed three-dimensionally within the height.
[0040]
According to the present embodiment, a three-dimensional intersection of the gold wires 5 can be realized by using a conventionally known wire bonding apparatus.
[0041]
Note that the present invention is not limited to the above-described embodiment, and may be embodied with appropriate modifications without departing from the spirit of the invention, for example, as described below.
(1) Changing the support height h2 of the gold wire 5 by appropriately changing the size and shape of the support bumps 10 or stacking them in multiple stages. For example, in the fifth embodiment, by making the wire support heights h2 of both the connecting members 61 different from each other, the horizontal portion 61b of the lower connecting member 61 is straddled by the horizontal portion 61b of the higher connecting member 61. Can be configured.
(2) Supporting the gold wire 5 in an inclined state with respect to the surface of the semiconductor chip 3 or the circuit board by changing the supporting height h2 of one of the pair of supporting portions 6.
(3) Instead of the gold wire 5, a metal wire of another material is used.
(4) A bonding pad is formed in advance at a position where each support bump 10 is to be formed by etching or the like, and the support bump 10 is formed on the bonding pad.
[0042]
【The invention's effect】
As described in detail above, according to the metal wire support structure according to the first and second aspects of the present invention, the metal wire can be supported at a predetermined height at a predetermined position on a semiconductor chip or a circuit board.
[0043]
In addition to the above effects, according to the invention of claim 3, the metal wire can be securely held at a predetermined position.
[0044]
Further, according to the stopper of the semiconductor acceleration sensor according to the fourth and fifth aspects of the invention, there is an excellent effect that the stopper can be formed at low cost.
[0045]
In addition to the above effects, according to the invention of claim 6, it is possible to reliably prevent an excessive relative displacement of the weight body in a predetermined direction.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a semiconductor acceleration sensor including a stopper according to a first embodiment of the present invention.
2A and 2B are diagrams showing the same stopper, wherein FIG. 2A is a plan view and FIG. 2B is a side view.
FIG. 3 is a sectional view taken along line III-III of FIG. 2;
FIG. 4 is a view showing a step of forming the stopper.
FIG. 5 is a view showing a step of forming a bump of the stopper.
FIG. 6 is a view showing a step of arranging a gold wire of the stopper.
FIG. 7 is a view showing a stopper according to a second embodiment of the present invention, wherein (a) is a plan view and (b) is a side view.
FIGS. 8A and 8B are views showing a stopper according to a third embodiment of the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a side view.
FIG. 9 is a sectional view taken along line IX-IX of FIG. 8;
FIG. 10 is a perspective view showing a method of forming a support portion of the stopper.
11A and 11B are diagrams illustrating a fence having a metal wire support structure according to a fourth embodiment of the present invention, wherein FIG. 11A is a plan view and FIG. 11B is a side view.
12A and 12B are diagrams illustrating a three-dimensional intersection of gold wires having a metal wire support structure according to a fifth embodiment of the present invention, wherein FIG. 12A is a plan view and FIG. 12B is a side view.
FIG. 13 is a perspective view showing the shape of a conventional gold wire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor acceleration sensor 2 Stopper 3 Semiconductor chip 3a Base 3b Beam 3c Weight 5 Gold wire 5a Supported part 6 Support part 10 Support bump 11 Depression 12 Pressing bump 13 Bump 15 First bonding 16 Second bonding 30 Stopper 40 Stopper 41 Stopper 41 Support part 42 Pad 43 Recess 50 Fence 60 Three-dimensional intersection P1 First bonding point P2 Second bonding point

Claims (6)

A metal wire supporting structure for supporting a supported portion, which is an intermediate portion in the length direction of the metal wire, at a predetermined point on a semiconductor chip or a circuit board,
A metal wire supporting structure, comprising: a pair of bumps formed on both sides of a central axis of the metal wire in the supported portion, wherein the supported portion is disposed in a concave portion formed between the bumps. A metal wire supporting structure for supporting a supported portion, which is an intermediate portion in the length direction of the metal wire, at a predetermined point on a semiconductor chip or a circuit board,
A groove formed in the upper surface of the pad and extending in a length direction of a central axis of the metal wire in the supported portion; and the recessed portion is formed in the concave portion. A metal wire support structure provided with. The metal wire supporting structure according to claim 1, further comprising a bump formed so as to press the supported portion from above the concave portion. A base and a weight supported so as to be relatively displaceable with respect to the base are provided on a semiconductor acceleration sensor arranged on a chip surface of a semiconductor chip, and an excessive relative displacement of the weight with respect to the base is provided. A stopper for preventing
A metal wire for preventing a relative displacement of the weight body beyond a predetermined limit is disposed so that the middle part in the length direction passes above the weight body, and both ends of the middle part in the length direction. A support portion for supporting each supported portion at a predetermined point on the base,
At least one of the support portions includes a pair of bumps formed on both sides of the central axis of the metal wire in the supported portion, and the supported portion is provided in a concave portion formed between the bumps. Stopper for semiconductor acceleration sensor. A base and a weight supported so as to be relatively displaceable with respect to the base are provided on a semiconductor acceleration sensor arranged on a chip surface of a semiconductor chip, and an excessive relative displacement of the weight with respect to the base is provided. A stopper for preventing
A metal wire for preventing a relative displacement of the weight body beyond a predetermined limit is disposed so that the middle part in the length direction passes above the weight body, and both ends of the middle part in the length direction. A support portion for supporting each supported portion at a predetermined point on the base,
At least one of the support portions includes a pad formed at a predetermined point on the base, and a groove-shaped recess extending in a length direction of a central axis of the metal wire at the supported portion is formed on an upper surface of the pad. A stopper for the semiconductor acceleration sensor, wherein the supported portion is disposed in the recess. The stopper of the semiconductor acceleration sensor according to claim 4, wherein the support portion includes a bump formed so as to press the supported portion from above the concave portion.

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