JP2015229775A - Contact jig for electroplating, semiconductor production apparatus and production method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact jig for electroplating which enables execution of electroplating by using the same jig even when metal electrodes to be plated have various pattern shapes and a semiconductor production apparatus and a production method of a semiconductor device using the contact jig for electroplating.SOLUTION: A contact jig 20 for electroplating includes a planar base member 21 composed of a conductive material, a plurality of contact electrodes 24 arranged on the surface of the base member 21 in a two-dimensional form, and the like. The base member 21 is coated with an electrical insulation material, and the contact electrodes 21 are coated with an electrical insulation material, except for the tip part. A semiconductor production apparatus includes the contact jig 20 for electroplating, a holding stage 7 for holding a semiconductor substrate, a state movement mechanism 8 which changes the relative position between the holding stage 7 and the contact jig 20, and the like.

Description

  The present invention relates to a contact jig for performing electroplating. The present invention also relates to a semiconductor manufacturing apparatus and a semiconductor device manufacturing method for performing electroplating on a semiconductor wafer using the contact jig.

  In a semiconductor chip such as a power transistor used for power conversion or the like, a metal electrode for flowing a current is formed on one or both of the back surface and the front surface of the semiconductor substrate. These metal electrodes are connected to terminals of an external circuit by ultrasonic bonding, soldering or the like using a wire or a plate material made of a metal material such as Al, Cu, or Au. In such a connection process, it is required to increase the thickness of the metal electrode in order to reduce damage to the semiconductor substrate.

  When the metal electrode is made thicker, the sputtering method, the vacuum deposition method, etc. have a slow film formation rate and the apparatus itself is expensive, so a plating method with a higher film formation rate and a lower cost is generally used. It is used.

  For example, in Patent Document 1, patterning is performed using a rubber mask that can be repeatedly used instead of a photoresist, and an end portion of an insulating-coated wiring is brought into contact with each of the patterned metal electrodes to be plated. The metal electrode is formed by plating.

  In Patent Document 2, a plurality of power supply electrodes are brought into contact with a metal electrode to be plated, and a current value flowing through each power supply electrode is individually controlled to form a metal electrode.

Japanese Patent Application Laid-Open No. 07-022425 Japanese Patent Laid-Open No. 02-101189 JP 2010-013680 A Japanese Patent Application Laid-Open No. 07-32111 JP 2002-069698 A JP 2001-323397 A JP 2002-332598 A JP 2000-017497 A

  As in Patent Documents 1 and 2, when electrode plating is performed by arranging electrode pins in accordance with each patterned metal electrode to be plated, it is necessary to change the arrangement of the electrode pins according to the type of patterning. Therefore, the change procedure becomes complicated in the case of small-quantity and multi-product production.

  Further, if a jig in which electrode pins are arranged in advance in accordance with patterning is used, it is necessary to prepare a jig for each type of semiconductor chip, resulting in an increase in cost.

  Furthermore, since the plating solution does not come into contact with the portion where the electrode pin is in contact, a portion where the metal electrode cannot be formed by plating is generated in the metal electrode to be plated.

  Also, after forming a seed electrode on the entire surface of the semiconductor substrate and patterning an insulating film such as a photoresist, forming a metal electrode on the metal electrode to be plated through the seed electrode by electroplating, and removing an unnecessary seed electrode, Since a process for patterning the seed electrode is newly required, the manufacturing cost increases.

  An object of the present invention is to provide an electroplating contact jig capable of performing electroplating using the same jig even when the metal electrode to be plated has various pattern shapes.

  Another object of the present invention is to provide a semiconductor manufacturing apparatus and a semiconductor device manufacturing method for performing electroplating on a semiconductor substrate using the electroplating contact jig.

In order to achieve the above object, a contact jig for electroplating according to the present invention comprises a flat base member made of a conductive material,
A plurality of contact electrodes arranged two-dimensionally on the surface of the base member;
The base member is coated with an electrically insulating material;
The contact electrode is covered with an electrically insulating material except for the tip.

The present invention is also a semiconductor manufacturing apparatus for performing electroplating on a semiconductor substrate,
The contact jig for electroplating, and
A holding mechanism for holding the semiconductor substrate;
And a moving mechanism for changing a relative position between the holding mechanism and the electroplating contact jig.

In addition, the method for manufacturing a semiconductor device according to the present invention includes a step of preparing a semiconductor substrate in which a metal pattern to be a plating base is formed in a piecewise manner
Immersing the semiconductor substrate in a plating solution in contact with the electroplating contact jig;
An electroplating step in which a current is passed between the electroplating contact jig and the counter electrode to perform metal plating on the metal pattern;
A step of changing a relative position between the semiconductor substrate and the contact jig for electroplating in the middle of the electroplating step.

According to the present invention, by arranging a plurality of contact electrodes two-dimensionally on the surface of the base member, even if the metal electrode to be plated has various pattern shapes, Electrical contact can be secured. As a result, even when the type of semiconductor chip is changed, electroplating can be performed using the same jig.
Further, by changing the relative position between the semiconductor substrate and the electroplating contact jig in the middle of the electroplating process, it is possible to suppress the variation in the plating amount due to the contact with the contact electrode.

It is sectional drawing which shows the structure of Embodiment 1 of this invention. It is a top view when a semiconductor manufacturing apparatus is seen from the anode side. It is sectional drawing which shows the process of forming the pattern of the to-be-plated metal electrode on a semiconductor substrate. It is a flowchart which shows the process of performing a plating process using the semiconductor manufacturing apparatus shown in FIG. It is sectional drawing which shows the structure of Embodiment 2 of this invention. It is sectional drawing which shows the structure of Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the configuration of Embodiment 1 of the present invention, and shows a state immediately after the start of electroplating. The bath 1 is filled with the plating solution 2 and is fixed to the bath 1 so that the anode 3 is positioned below the plating solution 2. The plating solution 2 and the anode 3 can be arbitrarily selected depending on the type of metal electrode to be electroplated. For example, when copper is formed as a metal electrode by electroplating, a solution such as copper sulfate, copper cyanide, copper pyrophosphate is used as the plating solution 2. In this solution, various additives are added to change the glossiness, hardness, and leveling properties, and the pH, temperature, and resistivity are adjusted. Further, for the anode 3, a metal such as phosphorous copper, electrolytic copper, high oxygen high purity copper or the like is used, and it is desirable to select an optimal copper for the plating solution 2.

  In addition, although copper plating was demonstrated above, the solution and anode material conventionally known can be used also about other electroplating, such as nickel plating and chromium plating, and this invention is applicable also in this case.

  The contact jig 20 is a flat base member 21 made of a conductive material, and is arranged two-dimensionally on the surface of the base member 21, and protrudes toward the plating object substantially parallel to the normal direction of the surface. A plurality of rod-shaped contact electrodes 24 and the like are provided and fixed to the bathtub 1. The base member 21 is covered with an electrically insulating material so that the plating material does not precipitate. Similarly, the contact electrode 24 is covered with an electrically insulating material except for the tip portion, and this tip portion functions as an electricity supply cathode 26 for ensuring electrical contact with the object to be plated.

  The base member 21 is disposed in parallel to the anode 3 and a plurality of through holes 25 are formed to further promote the flow of the plating solution 2.

  The contact jig 20 preferably includes a follow-up mechanism that follows the uneven shape of the plating object when the electricity supply cathode 26 contacts the plating object. In this embodiment, as such a follow-up mechanism, the contact electrode 24 is configured to be stretchable along the normal direction of the base member 21 using an elastic member such as a coil spring.

  In addition, the contact electrode 24 is preferably detachably attached to the base member 21, thereby improving maintainability. For example, even when there is a defect in one contact electrode 24, the performance can be maintained by replacing the defective part. As such a detachable mechanism, screwing, fitting or the like can be used.

  The base member 21, the contact electrode 24, and the electric supply cathode 26 are maintained at the same potential, and are connected to the anode 3 through an external power source PS.

  Next, a semiconductor manufacturing apparatus for performing electroplating on the semiconductor substrate 11 will be described. The semiconductor manufacturing apparatus includes a contact jig 20 as described above, a holding stage 7 that holds the semiconductor substrate 11, a stage moving mechanism 8 that changes the relative position of the holding stage 7 and the contact jig 20, and the like.

  On the surface of the semiconductor substrate 11, a large number of metal electrodes 12 to be plated, which are bases for electroplating, are arranged in a divided manner, and an insulating film for electrically separating the metal electrodes 12 to be plated around the electrodes. 13 is provided.

  The holding stage 7 includes a disk member having a flat surface that can be in close contact with the back surface of the semiconductor substrate 11, and a shaft member that extends along the central axis of the disk member. In order to hold the semiconductor substrate 11, a vacuum suction mechanism, an electrostatic chuck mechanism, an outer periphery clamp mechanism, and the like are mounted on the disk member.

  The stage moving mechanism 8 includes, for example, a robot arm to which the shaft member of the holding stage 7 is attached. And has a function of rotating around the Z direction.

  The stage moving mechanism 8 and the power source PS are connected to an external computer (not shown), and the electroplating process is controlled.

  FIG. 2 is a plan view of the above-described semiconductor manufacturing apparatus as viewed from the anode side. A large number of through holes 25 are formed in the base member 21 of the contact jig 20. The shape of the through-hole 25 is exemplified here as a hexagon that forms a honeycomb structure, but may be a polygon such as a triangle or a rectangle, or a circle. The contact electrode 24 shown in FIG. 1 is disposed at, for example, a hexagonal apex.

  The contact electrodes 24 can be arranged in an arbitrary density and distribution pattern, but the metal electrodes 12 to be plated are arranged in a sectioned manner on the semiconductor substrate 11. Therefore, when the contact jig 20 is brought into contact with the semiconductor substrate 11, it is desirable that at least one contact electrode 24, preferably two or more contact electrodes 24, be in electrical contact with each metal electrode 12 to be plated. Moreover, it is also preferable to move or rotate the position of the semiconductor substrate 11 during the electroplating process, thereby suppressing variation in the amount of electroplating. For this reason, it is preferable to determine the arrangement of the contact electrodes 24 and the movement pattern of the stage moving mechanism 8 by performing a simulation or the like in advance for all types of semiconductor elements to be electroplated.

  As described above, when the contact jig 20 according to the present invention is used, it is not necessary to prepare a dedicated jig for each product having different patterns of the metal electrode 12 to be plated. Furthermore, the plating film thickness distribution is leveled by determining the arrangement of the contact electrodes 24 in consideration of the stirring conditions of the plating solution 2 and the current distribution of the contact jig 20.

  FIG. 3 is a cross-sectional view showing a process of forming a pattern of the metal electrode 12 to be plated on the semiconductor substrate 11. First, as shown in FIG. 3A, a semiconductor substrate 11 in which a PN junction or the like is previously formed is prepared, and a metal electrode 12 to be plated is formed on the entire surface. The semiconductor substrate 11 is made of, for example, silicon, silicon carbide, gallium nitride, or the like. The metal electrode 12 to be plated is formed of a metal such as aluminum, titanium, copper, nickel, palladium, or an alloy thereof, or a laminated film thereof, and is formed using a sputtering method, a vacuum evaporation method, a CVD method, or the like. The Subsequently, in order to pattern the metal electrode 12 to be plated, the photoresist 14a is applied, exposed, and developed to form a pattern of the photoresist 14a.

  Next, as shown in FIG. 3B, the metal electrode 12 to be plated is patterned using a dry etching method or a wet etching method. At this time, each metal electrode 12 to be plated is electrically separated. Thereafter, the photoresist 14a is removed. Here, the method of patterning the metal electrode 12 to be plated using a photoresist mask has been described. However, as an alternative to the photoresist, a paste or ink containing a desired metal can be used, for example, an inkjet method, an offset printing method, Patterning may be performed by coating using a screen printing method or the like. Such a method can generally perform patterning at a lower cost than a method using a photoresist mask. Of course, there is no problem even if these methods are combined.

  Next, as shown in FIG. 3C, an insulating film 13 is formed by a CVD method or application / heating of a solution so as to cover the semiconductor substrate 11 and the metal electrode 12 to be plated. As the insulating film 13, for example, silicon oxide, silicon nitride, polyimide, or the like is generally used.

  Next, as shown in FIG. 3D, by using existing technology, the photoresist 14b is applied, exposed and developed so as to cover the insulating film 13 in the region where the metal electrode 12 to be plated does not exist. Then, a pattern of the photoresist 14b is formed.

  Next, as shown in FIG. 3E, the insulating film 13 is patterned using a dry etching method or a wet etching method. Thereafter, the photoresist 14b is removed.

  Then, you may perform the thin finishing process which grinds the back surface of the semiconductor substrate 11, the process of forming a metal electrode in the back surface of the semiconductor substrate 11, etc. In addition, these processes can also be performed after implementing the electroplating process which concerns on this invention.

  FIG. 4 is a flowchart showing a process of performing plating using the semiconductor manufacturing apparatus shown in FIG. Before performing the electroplating treatment, degreasing cleaning and cleaning may be performed to clean the surface of the metal electrode 12 to be plated. Further, when the surface of the metal electrode 12 to be plated is made of a material that cannot be electroplated directly and favorably on the metal electrode 12 to be plated, a zincate process, an electroless plating process, a strike plating process, etc. are performed to achieve a good electrical property. You may perform the process of surface-treating to the to-be-plated metal electrode 12 so that a plating process can be performed.

  First, as shown in FIG. 3, a semiconductor substrate 11 on which a metal electrode 12 to be plated serving as a plating base is formed in a divided manner is prepared, and then set on a holding stage 7 that is retracted from the bathtub 1 (step S1).

  Next, the stage moving mechanism 8 is operated to move the holding stage 7 into the bath 1 so as to be immersed in the plating solution 2 and to bring the metal electrode 12 to be plated into contact with the electric supply cathode 26 of the contact electrode 24 (step) S2). At this time, the contact electrode 24 in contact with the insulating film 13 can be shrunk in accordance with the difference between the thickness of the metal electrode 12 to be plated and the thickness of the insulating film 13. In addition, the stress applied to the insulating film 13 can be reduced, and damage applied to the semiconductor substrate 11 can be suppressed.

  Next, energization by the power source PS is started, a positive potential is applied to the anode 3 and a negative potential is applied to the electricity supply cathode 26, and a constant current is applied to the metal electrode 12 to be plated for a predetermined time. (Step S3), and then the current is interrupted (step S4). At this time, the electroplating processing time is set to be a fraction to a hundredth of the processing time to reach the required metal electrode film thickness, that is, the current energization / interruption cycle is several to several hundred times. It is preferable to divide into two.

  Next, it is determined whether the accumulated time of the electroplating treatment time has reached the treatment time for reaching the required metal electrode film thickness (step S5). When the processing time has not been reached, the stage moving mechanism 8 is operated to rotate the holding stage 7 or move up and down, left and right to temporarily separate the electric supply cathode 26 from the metal electrode 12 to be plated. The relative position is changed, and the electric supply cathode 26 is brought into contact with a place other than the contact with the electric supply cathode 26 in the past (step S6). Subsequently, steps S2 to S5 are repeated.

  On the other hand, when the necessary processing time is reached in step S5, the stage moving mechanism 8 is operated, the holding stage 7 is taken out from the bathtub 1, washed and dried (step S7), and then the semiconductor substrate 11 is held. It is removed from the stage 7 (step S8). The removed semiconductor substrate 11 is appropriately heat-treated to remove moisture in the film.

  When the electroplating process is performed using the semiconductor manufacturing apparatus having such a configuration, the location where the electricity supply electrode 26 contacts the metal electrode 12 to be plated can be changed many times during the electroplating process. Further, the plurality of electricity supply electrodes 6 can be brought into contact with each of the divided patterns of the metal electrode 12 to be plated.

  By performing the electroplating process while moving the electricity supply electrode 6 with respect to the pattern of the metal electrode 12 thus divided, the plating amount does not deposit due to the contact with the electricity supply electrode 6. Can also be plated. At this time, although the electroplating process time is reduced at the place where the electricity supply electrode 6 is in contact, the cross-sectional area of the electricity supply electrode 6 is sufficiently small with respect to the metal electrode 12 to be plated, and the electroplating process routine is short. The thickness of the metal electrode at the location where the electricity supply electrode 6 is in contact is within the range of variation error.

  Further, it is expected that the number of the electric supply electrodes 6 that are in contact with the divided pattern of each metal electrode 12 to be plated is different and a difference appears in the current value. Since the value changes for each routine (step S3), the total current value for each pattern is made uniform. Further, the uniformity can be promoted by optimizing the conductivity of the plating solution 2.

  Moreover, it is not necessary to prepare a dedicated jig according to the pattern of the metal electrode 12 to be plated, and an electroplating process can be performed using the same contact jig 20 for a group of products having different patterns of the metal electrode 12 to be plated. It becomes possible. Therefore, the jig creation cost can be reduced, and the trouble of managing the dedicated jig can be saved.

  Furthermore, since electricity can be supplied through the electricity supply electrode 6 to each of the divided patterns of the metal electrode 12 to be plated, the formation and patterning of the seed layer for electricity supply can be omitted, so that the manufacturing cost can be reduced.

  In the present embodiment, the case where the anode 3 and the holding stage 7 are arranged horizontally has been described. However, the present invention can also be applied to the case where the anode 3 and the holding stage 7 are arranged vertically.

Embodiment 2. FIG.
FIG. 5 is a cross-sectional view showing the configuration of Embodiment 2 of the present invention, and shows a state immediately after the start of electroplating. The contact jig 20 according to the present embodiment has the same configuration as that of the first embodiment, but as a follow-up mechanism, the contact electrode 24 is configured to be able to be bent in the lateral direction using an elastic member such as a leaf spring. Is different.

  When the stage moving mechanism 8 is operated so that the electricity supply electrode 26 comes into contact with the metal electrode 12 to be plated, if the contact electrode 24 has a rod shape or a plate shape, it can be bent in the lateral direction. For this reason, it is possible to ensure a stable contact strength without precisely aligning the electricity supply electrode 26 and the metal electrode 12 to be plated. In addition, excessive stress is not applied to the insulating film 13, and defects due to damage of the insulating film 13 can be reduced.

  According to this configuration, even when the plated metal electrode adheres to the electricity supply cathode 26 and the expansion / contraction function is impaired, electrical contact with the electricity supply cathode 26 can be ensured according to the uneven shape of the semiconductor substrate 11. In addition, the probability of the semiconductor substrate 11 being damaged due to excessive stress can be reduced.

Embodiment 3 FIG.
FIG. 6 is a cross-sectional view showing the configuration of Embodiment 3 of the present invention, and shows a state immediately after the start of electroplating. The contact jig 20 according to the present embodiment has the same configuration as that of the first embodiment, but the base member 21 is configured to be bent in the vertical direction using an elastic member such as a leaf spring as a follow-up mechanism. Is different.

  When the stage moving mechanism 8 is operated and the electricity supply electrode 26 comes into contact with the metal electrode 12 to be plated, if the base member 21 is plate-shaped, it can be bent in the vertical direction. For this reason, it is possible to ensure a stable contact strength without precisely aligning the electricity supply electrode 26 and the metal electrode 12 to be plated. In addition, excessive stress is not applied to the insulating film 13, and defects due to damage of the insulating film 13 can be reduced.

  According to this configuration, even when the plated metal electrode adheres to the electricity supply cathode 26 and the expansion / contraction function is impaired, electrical contact with the electricity supply cathode 26 can be ensured according to the uneven shape of the semiconductor substrate 11. In addition, the probability of the semiconductor substrate 11 being damaged due to excessive stress can be reduced.

1 bath, 2 plating solution, 3 anode, 7 holding stage,
8 stage moving mechanism, 11 semiconductor substrate, 12 metal electrode to be plated,
13 insulating film, 14a, 14b photoresist,
20 contact jig, 21 base member, 24 contact electrode,
25 through hole, 26 electricity supply cathode.

Claims (8)

A flat base member made of a conductive material;
A plurality of contact electrodes arranged two-dimensionally on the surface of the base member;
The base member is coated with an electrically insulating material;
The contact electrode for electroplating, wherein the contact electrode is coated with an electrically insulating material except for a tip portion.   The contact jig for electroplating according to claim 1, wherein a plurality of through holes are formed in the base member.   The contact jig for electroplating according to claim 1, further comprising a follow-up mechanism that follows the uneven shape of the object to be plated when the tip of the contact electrode contacts the object to be plated.   The contact jig for electroplating according to claim 3, wherein, as the follow-up mechanism, the contact electrode is configured to be stretchable along the normal direction of the base member using an elastic member.   The contact jig for electroplating according to claim 3, wherein, as the follow-up mechanism, the contact electrode is configured to be bent using an elastic member.   4. The contact jig for electroplating according to claim 3, wherein the base member is configured to be bendable using an elastic member as the follow-up mechanism. A semiconductor manufacturing apparatus for electroplating a semiconductor substrate,
The contact jig for electroplating according to any one of claims 1 to 6,
A holding mechanism for holding the semiconductor substrate;
A semiconductor manufacturing apparatus comprising: a moving mechanism that changes a relative position between the holding mechanism and the electroplating contact jig. A step of preparing a semiconductor substrate in which a metal pattern to be a plating base is formed in a piecewise manner;
A step of immersing the semiconductor substrate in a plating solution in contact with the electroplating contact jig according to any one of claims 1 to 6;
An electroplating step in which a current is passed between the electroplating contact jig and the counter electrode to perform metal plating on the metal pattern;
Changing the relative position between the semiconductor substrate and the electroplating contact jig in the middle of the electroplating step.

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