JP4466495B2 - Manufacturing method of semiconductor device - Google Patents

Description

The present invention, when performing the isolation between the electrodes by grinding or cutting, a method for manufacturing a semiconductor device can be suppressed to cause the element characteristic variations due to static electricity or the like generated during grinding or cutting.

Conventionally, Al is generally used as an electrode of a semiconductor device in which a semiconductor element such as a power element or a diode is formed. However, Al has a problem of corrosion or a problem of insufficient adhesion to a bonding wire. There is. For this reason, a technique of laminating a metal layer such as Ni or Au on the Al surface by an electroless plating method is used.
JP-A-2005-64451

  However, the electroless plating as described above, for example, increases the thickness of the metal layer such as Ni, and the difference between the linear expansion coefficient of the metal layer such as Ni and the linear expansion coefficient of other materials in the semiconductor device results in the semiconductor. The chip may be warped.

  For this reason, if the metal layer such as Ni is formed by deposition, sputtering, vapor deposition or the like instead of electroless plating so that the metal layer such as Ni can be formed thin, the warp of the semiconductor chip as described above Can be suppressed.

  However, when a metal layer such as Ni is formed by deposition, sputtering, vapor deposition, etc., it will be formed on the entire surface of the wafer. Therefore, for insulation between electrodes, a metal such as Ni by deposition, sputtering or vapor deposition. After the layer is formed, it must be patterned. At this time, the material used at the time of etching differs depending on the type of the metal layer such as Ni. Therefore, as the metal layer is multi-layered, more types of etching materials must be prepared.

  For this reason, the present inventors considered removing the metal layer all at once regardless of the material of the metal layer by partially grinding the metal layer such as Ni by machining. However, when performing such machining, electric charges are generated in the semiconductor element due to electric charges generated by cutting off the previously integrated part during grinding or static electricity generated by friction with a grinding tool. Will be charged, causing variations in device characteristics. As a countermeasure against such charge, it is conceivable to separately provide a protection circuit in a semiconductor chip constituting the semiconductor device. However, since the protection circuit is required, the area of the semiconductor chip is increased. In the case where the above function is not sufficient, fluctuations in device characteristics cannot be prevented, and there is a possibility of blocking destruction.

In view of the above points, the present invention provides a method for manufacturing a semiconductor device capable of suppressing element characteristic fluctuations due to static electricity or the like generated during grinding or cutting when insulating separation between electrodes is performed by grinding or cutting . With the goal.

In order to achieve the above object, according to the first to fourth aspects of the present invention, a first metal film (1) electrically connected to a desired location of a semiconductor element is formed on the semiconductor substrate (1) on which the semiconductor element is formed. 2) and a protective film (3) having a contact hole (3a) exposing a region to be a pad in the first metal film (2), and then the surface of the protective film (3) and the first metal film (2 ), A second metal film (4) is formed on the surface of the region to be a pad by any one of deposition, sputtering, and vapor deposition, and is further used for machining by machining. Using the jig (10) in a grounded state, the protective film (3) and the second metal film (4) are ground or cut to the middle of the thickness of the protective film (3) to contact the protective film (3). On the side wall surface of the hole (3a) and the first metal film (2) Is characterized by leaving the second metal film (4) takes on the surface of the region to be a pad.

Thus, by forming the second metal film (4) formed on the entire surface of the wafer on the surface of the protective film (3) while forming the second metal film (4) by deposition, sputtering or vapor deposition, An unnecessary part of the second metal film (4) is removed together with a part of the protective film (3). At this time, unnecessary parts are removed by machining and the jig (10) is in a grounded state. Therefore, static electricity generated at the time of grinding or cutting , electric charges generated when the protective film (3), etc. are cut off are removed from the jig. It is possible to prevent the semiconductor element from being absorbed through (10) and being charged.

For this reason, when performing insulation isolation between electrodes by grinding or cutting , it can be set as the manufacturing method of the semiconductor device which can suppress an element characteristic fluctuation | variation by the static electricity etc. which generate | occur | produce at the time of grinding or cutting .

  For example, as shown in claim 2, an organic resin material can be used as the protective film (3).

The invention according to claim 4 is characterized in that an atmosphere of at least a portion where grinding or cutting is performed during machining is a conductive atmosphere.

In this way, if the grinding or cutting part is wrapped in a conductive atmosphere, the charge can be prevented from being charged.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
1 is a cross-sectional view of a semiconductor device manufactured using a manufacturing method to which an embodiment of the present invention is applied.

As shown in FIG. 1, the semiconductor device includes an Al film 2 on the surface of a semiconductor chip 1 in which a semiconductor element such as a power element or a diode is formed via an insulating film (not shown) made of SO ₂ or the like. Is formed. The Al film 2 corresponds to the first metal film in the present invention, and is electrically connected to a desired portion of the semiconductor element formed in the semiconductor chip 1 through a contact hole formed in an insulating film (not shown). It has a structure.

  A protective film 3 is formed on the surface of the Al film 2 and the surface of an insulating film (not shown). This protective film 3 is made of a material that can be cut without being deformed by a cutting tool 10 (see FIG. 2B) described later, that is, a material that is not a brittle material and has a high adhesion to Au. For example, an organic resin material such as polyimide. For example, in FIG. 1, the thickness of the protective film 3 is about 10 μm.

  Although the thickness of the protective film 3 is 10 μm here, it does not necessarily have to be this value. For example, the thickness of the protective film 3 can be changed within a range of 2 μm to 30 μm. Here, the lower limit is set to 2 μm in consideration of positioning accuracy on the machine side such as cutting and grinding, and the upper limit is set to 30 μm because the film thickness distribution is reduced by spin coating. This is because the upper limit that can be applied is this value. Moreover, it is preferable when the film thickness of the protective film 3 shall be 7 micrometers-20 micrometers. When processing with the current wafer thickness variation and cutting machining accuracy, the film thickness of the protective film 3 is preferably 7 μm or more in consideration of the process capability at the time of mass production. On the other hand, since there is an upper limit on the amount of cutting once, if it is too thick, it must be cut repeatedly, and the total processing time becomes longer. Further, considering the process capability and the economic efficiency in mass production with respect to the processing yield, it is optimal that the thickness of the protective film 3 is 10 μm or more and 15 μm or less.

  Further, a metal film 4 electrically connected to the Al film 2 is formed on the side wall surface of the contact hole 3 a of the protective film 3 and the surface of the Al film 2 exposed from the opening of the protective film 3. This metal film 4 corresponds to the second metal film in the present invention.

  In the present embodiment, the metal film 4 is composed of a laminated film in which a plurality of types of metals are laminated, and in order from the bottom layer, an Al layer (first layer) having a high adhesion reliability with the Al film 2 and an Al layer. Ti layer (second layer) that plays a role in blocking the diffusion of tin in the bonding wire 6 when solder is bonded to the surface of the metal film 4 and Ni that blocks tin similarly to the Ti layer The structure has an Au layer (fourth layer) for preventing oxidation of the surface of the layer (third layer) and the Ni layer and improving solder wettability.

  A solder (not shown) is joined to the surface of the metal film 4 and the solder is electrically joined to the semiconductor element formed on the semiconductor chip 1 through the metal film 4 and the Al film 2. .

  Next, a method for manufacturing a semiconductor device in the present embodiment will be described. FIG. 2 shows a cross-sectional view of the semiconductor device in the present embodiment during the manufacturing process, which will be described based on this drawing.

  As shown in FIG. 2A, after forming an insulating film (not shown) on the surface of the semiconductor chip 1 in which a power element, a diode, and the like are formed, a contact hole is formed at a desired position of the insulating film. Then, the Al film 2 is formed on the insulating film, and the Al film 2 is patterned, so that electrical connection with a desired position of the semiconductor element is performed through the contact hole formed in the insulating film. Subsequently, a protective film 3 is formed on the surfaces of the Al film 2 and an insulating film (not shown) with polyimide, for example, with a thickness of, for example, about 15 μm, and then contact etching is performed to form a contact hole 3a. Expose position. Then, the metal film 4 is formed by deposition, sputtering or vapor deposition. At this time, the metal film 4 is formed on the entire surface of the wafer.

  In the step shown in FIG. 2B, the cutting tool 10 made of diamond for grinding is connected to the GND wiring 11 to be in a grounded state, so that no charge is accumulated in the cutting tool 10, and the cutting tool 10 is formed within the wafer surface. , The upper portions of the metal film 4 and the protective film 3 are scraped off by the cutting tool 10. At this time, for example, the cutting tool 10 is scanned so that only about several μm from the surface of the protective film 3 can be removed by the cutting tool 10. In other words, the protective film 3 is scraped off to the middle of the thickness of the protective film 3, and the protective film 3 is left to a position above the surface of the metal film 4 formed on the surface of the Al film 2.

  The surface grinding with the cutting tool 10 is generally used in the metal processing technique, but the grinding depth will vary somewhat. Considering this variation, even if the variation occurs, the surface to be ground is protected between the surface of the metal film 4 formed on the surface of the protective film 3 and the surface of the protective film 3 before grinding. The thickness of the film 3 is set.

  In this manner, as shown in FIG. 1, a structure in which the metal film 4 is formed only on the side wall surface of the contact hole 3a of the protective film 3 and the surface of the Al film 2 exposed from the contact hole 3a is completed.

  Thereafter, by joining with solder or the like, an electrical connection structure between the semiconductor device and the external wiring is completed.

  According to the manufacturing method of the semiconductor device of the present embodiment described above, the metal film 4 is formed by deposition, sputtering, or vapor deposition that makes it difficult to transmit the corrosive medium from between the metal film 4 and the protective film 3. The metal film 4 formed on the entire surface of the wafer is formed on the surface of the protective film 3 so that unnecessary portions of the metal film 4 are removed together with a part of the protective film 3. At this time, unnecessary parts are removed by machining using the cutting tool 10 and the cutting tool 10 is grounded, so that static electricity generated at the time of grinding or the charge generated when the protective film 3 and the like are cut off are generated by the cutting tool 10. It is possible to prevent the semiconductor element from being charged by being absorbed and transmitted.

  For this reason, when performing insulation separation between electrodes by grinding, it can be set as the manufacturing method of the semiconductor device which can suppress that an element characteristic fluctuation | variation arises by the static electricity etc. which generate | occur | produce at the time of grinding.

(Other embodiments)
In the above embodiment, the bit 10 is grounded to prevent the charge from being charged due to static electricity or the like. However, as shown in the manufacturing process diagram of the semiconductor device shown in FIG. In addition, an atmosphere adjusting device 20 such as an air blower or a CO ₂ bubbler may be used to enclose the inside of the apparatus to be ground or the grinding portion with a conductive atmosphere, that is, a gas with enhanced conductivity. Thus, if the grinding part is wrapped in a conductive atmosphere, the charge can be further prevented from being charged. For example, by introducing CO ₂ into the atmosphere like a CO ₂ bubbler, it is possible to increase the conductivity of the gas in the atmosphere.

In the above embodiment, using the byte 10 as jig has been described by byte 10 for machining to cut the metal film 4 and the protective film 3 Ken, other, may be carried out cutting using a multi-blade tool as a jig.

It is a figure showing the section composition of the semiconductor device in a 1st embodiment of the present invention. FIG. 3 is a cross-sectional view showing a manufacturing process of the semiconductor device shown in FIG. 1. It is sectional drawing which showed the manufacturing process of the semiconductor device shown in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip (semiconductor substrate), 2 ... Al film, 3 ... Protective film, 4 ... Metal film,
10 ... bite, 20 ... atmosphere adjusting device.

Claims (4)

Preparing a semiconductor substrate (1) on which a semiconductor element is formed;
Forming a first metal film (2) electrically connected to a desired location of the semiconductor element on the semiconductor substrate (1);
Forming a protective film (3) having a contact hole (3a) exposing a region to be a pad in the first metal film (2) on the first metal film (2);
The second metal film (4) is formed on the surface of the protective film (3) and the surface of the region to be the pad in the first metal film (2) by any one of deposition, sputtering, and vapor deposition. )
In the machining, the jig (10) used for machining is used in a grounded state, and the protective film (3) and the second metal film (4) are in the middle of the thickness of the protective film (3). grinding or cutting up, leaving the second metal film (4) on the surface of the region to be the pad in the the side wall surface first metal layer (2) of the contact hole in the protective film (3) (3a) And a method of manufacturing a semiconductor device.   The method for manufacturing a semiconductor device according to claim 1, wherein, in the step of forming the protective film (3), the protective film (3) is formed of an organic resin material.   The method of manufacturing a semiconductor device according to claim 1, wherein the machining is performed by performing cutting using a tool or a multi-blade tool as the jig. 4. The method of manufacturing a semiconductor device according to claim 1, wherein an atmosphere of at least a portion where the grinding or cutting is performed during the machining is a conductive atmosphere. 5.

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