Device for galvanizing member-shaped substrates

Abstract

A device for galvanizing of member-shaped substrates includes a base (1), an adapter (5) supported on the base (1) for supporting a to-be galvanized member-shaped substrate (2), an upper sealing ring for securing the to-be-galvanized member-shaped substrate to the adapter (5), an annular complementary member (10) located opposite the upper sealing ring (3) and having counter-recesses complementary to a recess formed in the lower end of the sealing ring (3) and in which a respective O-ring (7) is received, with the annular complementary member (10) being mounted in the base (1) without any side clearance and sealing, together with the sealing ring (3), with the respective upper and lower O-rings (6, 7) being received in respective recess, an electrolyte region.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for galvanizing member-shaped substrates, in particular wafers.

2. Description of the Prior Art

Wafers are basically flat-shaped round parts which usually form a basis for chip production in the area of the semiconductor technology. The wafers are usually formed of semiconductor materials of the fourth group of the Periodical system, e.g., of silicon or germanium.

Because the fourth group of the chemical Periodical system is located in the middle between the metals of the first group and the non-metal of the eighth group of the Periodical system, the elements of the fourth group are neither ion-conducting metals no ion-non-conducting non-metals. Rather, they are quasi semi-metals with so-called ion, e.g., electron-semiconducting characteristics.

The contemporary technology uses these semiconducting characteristics, which permits to use minimum space for effecting different functions where previously a thousand time greater space dimensions, were required.

As a rule, wafers are thin round members with a thickness of about 1 mm and with a diameter from about 100 mm to 300 mm, and which are cut out from so-called monocrystals. For special applications, wafer upper surfaces needs to be subjected to a special treatment. The wafer surface can be treated mechanically, e.g., be polished or by being covered with different types of coating. A wafer surface can be coated partially or completely. The type of the coating generally depends on the function to be performed by a wafer. The surface treatment includes, e.g., lacquering or similar processes. In particular, however, galvanization is used when a wafer surface should be provided with a metallic layer.

A metal layer, which is formed on a wafer surface by galvanization, makes the respective portion of the wafer electroconductive. The galvanization method has a certain advantage which consists in that the metal precipitation on a wafer can take place from an aqueous solution of metal salts dissolved in the distilled water. These metal salt solutions are called electrolyte solutions or simply electrolytes.

Galvanization methods provide many possibilities for obtaining functional characteristics (features) of a metal coating applied to a wafer surface. Because metal salts easily dissolve in wafer, different metals can be precipitated on a wafer from aqueous solutions of metal salts. Dependent on the required conductive characteristics, different metals can be used for coating, from poor conductive chrome up to good conductive metals such as copper, silver, or gold.

The galvanization process can be optimally used because separate parameter of the process technology which affect the structure of a metal layer, are easily varied.

These parameters are:

• • concentration of the salt content of electrolyte baths,
  • current density and current voltage of the process energy which is fed from a current source via cathode and anode.

The galvanization technology is well known, has wide application, and does not need to be described here further.

However, wafer galvanization technology is a special case of galvanization. Its advantages proved themselves in practice.

A conventional wafer galvanizing device has a base for supporting a wafer and a sealing ring for securing the wafer on an adapter supported on the base. The entire system is held together by a union nut. At the free end of the sealing ring, there is provided an O-ring. For sealing the electrolyte region or bath, there is provided another, side O-ring which also seals the so-called guide gap through which one end of both the sealing ring and of the union nut extend.

The problem with known galvanizing devices consists in adequate sealing of the region of the electrolyte bath between the wafer top surface and the wafer bottom surface. The sealing generally is effected with the sealing ring. The electrolyte bath is sealed, as discussed above, with the side O-ring. However, the side O-ring can be mounted only at a dry condition, i.e., with an empty bath, which is a serious drawback. With multiple manipulations, the system, because of the dry-wet exchange, is susceptible to drain or seepage of the electrolyte.

Further, the existing temperature differences play an important role in view of different specific thermal expansion coefficients of the device elements. The sealing should be 100%-reliable. In case of a not sufficient sealing in the device system, process disturbances take place. And, as with all process disturbances and interruptions, the product quality of the initial product is not obtainable when the process is resumed.

Because of poor quality resulting from a process failure, and a high percentage of the rejected products and with high costs of initial row materials used in the wafer galvanization process, the manufacturing costs are very high.

A particular weak point of the conventional galvanizing device is the side clearance between the portion of the sealing ring, which is received in the guide gap, and the device base. The sealing of this clearance is effected with the relatively large side O-ring. The drawback of this O-ring consists in that it tends to roll-over or is subjected, during the adjustment of the sealing ring, to friction. Both rolling-over and friction results in the side O-ring wear, which leads to seepage of the electrolyte. Further, up and down movement of the sealing ring leads to formation of fissures in the side O-ring which also leads to seepage of the electrolyte. Also, mounting of the side O-ring is rather complicated. Before being placed in a respective annular groove, the side O-ring is stretched, which also damages the side O-ring.

For galvanizing wafers having a diameter of about 300 mm as well as for other diameters, it is necessary that the elements of the galvanizing device be precisely adapted to each other or be registered with each other so that no side clearance is formed. It also necessary to insure an easy mounting of O-rings in respective recesses. However, these requirements are particularly important for the new generation of wafer members with a diameter of 300 mm. A precise registration of the sealing ring with integrated therein O-rings relative to the device base should be maintained despite possible dimension variations caused by thermal expansion, and wear of the sealing system, in particular of the O-rings, should be absolutely minimal.

Accordingly, an object of the present invention to provide a galvanizing device having a good sealing that would prevent seepage of the electrolyte between the wafer upper region and the wafer lower region.

Another object of the present invention is to provide a galvanizing device with an easily mountable sealing system.

A further object of the present invention is to provide a galvanizing device with the separate elements of the device being precisely adapted to each other so that no side clearance between the sealing ring and the base is formed.

A still further object of the present invention is to provide a galvanizing system in which the elastic, separate sealing elements, namely, O-rings are arranged along a vertical line to exclude friction of the O-ring surfaces from the very beginning.

A yet another object of the present invention is to provide a galvanizing device in which the O-rings after being placed in predetermined spaces, are not touched anymore.

SUMMARY OF THE INVENTION

These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a galvanizing device for member-shaped substrates, and in particular wafers, having a base, an adapter supported on the base for supporting a to-be galvanized member-shaped substrate, an upper sealing ring for securing the to-be-galvanized member-shaped substrate to the adapter and provided at its opposite upper and lower ends with recesses for receiving respective O-rings, an annular complementary sealing member located opposite the upper sealing ring and having counter-recesses complementary to a recess formed in the lower end of the sealing ring and in which a respective O-ring is received, the annular complementary member being mounted in the base without any side clearance and the annular member sealing, together with the sealing ring, with the respective O-rings being received in respective recess, an electrolyte region, and a union nut for securing the entire system together.

The complementary sealing member can be pressed against the upper sealing ring also with the union nut when a buffer elastic member is provided between the bottom of the device and the lower sealing member, which can have a shape of a ring or a disc. For security's sake, in such a case, a bellows seal is provided between the lower annular ring member and the device base. The bellows can be arranged horizontally or vertically between the lower annular sealing member and the base, and is formed, as a rule, of rubber or a rubberized textile material.

The bellows can be provided with a channel for a pneumatic or hydraulic medium for applying pressure to the lower annular sealing member.

When the lower annular sealing member is formed with a solid bottom surface, a flexible diaphragm, which is subjected to a pneumatic or hydraulic pressure, can be used for pressing the it toward the upper sealing ring.

The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however both as its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:

FIG. 1 a cross-sectional view of a prior art galvanizing device for members;

FIG. 2 a cross-sectional view of a first embodiment of a galvanizing device for members according to the present invention;

FIG. 3 a cross-sectional view of a second embodiment of a galvanizing device for members according to the present invention;

FIG. 4 a cross-sectional view of a third embodiment of a galvanizing device for members according to the present invention;

FIG. 5 a cross-sectional view of a fourth embodiment of a galvanizing device for members according to the present invention;

FIG. 6 a cross-sectional view of a fifth embodiment of a galvanizing device for members according to the present invention; and

FIG. 7 a cross-sectional view of a sixth embodiment of a galvanizing device for members according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows, as memberussed above, a prior art member (wafer) galvanizing device B. The device has a base 1 for supporting a wafer 2 and a sealing ring 3 for securing the wafer 2 on an adapter 5 supported on the base 1. The entire system is held together by a union nut 4 which has an outer thread cooperating with an inner thread provided in the base 1. At the free end of the sealing ring 3, there is provided an O-ring 6. For sealing the electrolyte region or bath, there is provided a sealing side O-ring 18, which also seals the guide gap 21.

A first embodiment of a wafer galvanizing device according to the present invention is shown in FIG. 2. In the wafer galvanizing device A shown in FIG. 2, in addition to the O-ring 6, which is located in a recess provided at the free end of the sealing ring 3, there is provided a second O-ring 7 arranged in a recess formed at the opposite end of the sealing ring 3. Alternatively, the second sealing O-ring 7 can be located in a recess formed in a complementary annular sealing member 10 provided at the opposite end of the sealing ring 3. The annular sealing member 10 insures an exact mounting of the sealing ring 3 on an intermediate member 16, substantially without any clearance therebetween. When the annular sealing member 10 is used, it is connected with the base 1 by an elastic bellows 9, which insures a further sealing of the electrolyte region. The use of the second O-ring 7, together with the annular sealing member 10 and the bellows 9, permitted to eliminate the O-ring 18, the drawbacks of which were memberussed above. In the embodiment of the inventive wafer galvanizing device shown in FIG. 2, elastic buffer ring member 8 is provided between the annular sealing 10 and the device base 1. The ring member 8 provides for a uniform distribution of stresses in the system.

A wafer galvanizing device e, which is shown in FIG. 3, differs from that of FIG. 2 by having a wide buffer ring 8 and a bellows 9 that extends not horizontally as in the embodiment of FIG. 2, but vertically. The union nut 4 insures sealing engagement of the O-rings 6 and 7 with respective parts.

In the embodiment of a wafer galvanizing device according to the present invention, which is shown in FIG. 4, in the device 2, the annular sealing 10 is formed with a plate-like surface, with the second O-ring 7 being located in a recess formed in the annular end surface of the annular sealing 10. For compensating a pressure force applied to the annular sealing 10, thee is provided an elastic buffer ring member 12 arranged in an annular recess formed in the intermediate member 16. To provide for a sealing engagement of the O-rings 6 and 7 with the wafer 2 and the sealing ring 3, respectively, a mechanically, pneumatically or hydraulically driven pressure device 11 is used. The current-conducting electrodes 20 project into another annular recess formed in the intermediate member 16.

A wafer galvanizing device E, which is shown in FIG. 5, represents a combination of the devices C and D shown in FIGS. 3 and 4, respectively, together with a height-adjusting member 13 with which the height of the entire system is adjusted.

In a wafer galvanizing device F, which is shown in FIG. 6, double-side bellows 9 are used for connecting the annular sealing 10 with the base 1. The inner chambers 14 of the bellows communicate via a system of channels with a source 19 of a pneumatic or hydraulic pressure medium with which a pressure of the annular sealing 10 on the sealing ring 3 is regulated. This insures that after the O-rings are mounted, no further mechanical adjustment is necessary, in particular, because the O-ring system is loaded in the vertical direction. In this case, a dynamic sealing pressure is applied to both O-rings 6 and 7, and they are not subjected to any frictional load. A further advantage of the device F shown in FIG. 6 consists in that with a change or interruption of the process, O-rings 6 and 7 can be easily removed and replaced. The O-rings 6 and 7 are subjected only to a minimal wear, while insuring a very reliable sealing of the electrolyte medium.

A wafer galvanizing device G according to the present invention, which is shown in FIG. 7, represent a combination of the devices D and F shown in FIGS. 4 and 6, with further modifications. The pressure to the annular sealing 10 is applied by a flat diaphragm 17 which insures a uniform application of pressure to the bottom of the annular sealing 10 which, in turn, insures a uniform application of pressure to both O-rings 6 and 7. The uniform application of pressure to O-rings 6, 7 is further facilitated by using the elastic buffer ring member 12. The pressure applied by the diaphragm 17 is regulated with the pressure medium 19. All of the elements of the device G are ideally centered and dynamically preloaded.

The wafer galvanizing device according to the present invention represents a further technical advance of the galvanizing technology and noticeably reduces possible errors of the galvanizing process. Further, the inventive wafer galvanizing device permits to significantly reduce a harmful influence of a galvanizing process on the environment.

The production of semiconductors on the basis of silicon or germanium or of other types of semiconductors is an energy-intensive process and, together with other intermediate processes, requires extensive disposal measures to prevent a harmful effect on the environment in case of a production errors.

Due to provisions of means for vertical adjustment of the inventive device, a vertical linear pressure is applied to elements of the device. Despite that, separate elements of the device can be mounted based on another principle.

Due to the vertically center mounting of the elements of the device, the edge galvanization of a wafer remains uniform and error-free. The failure rate during the production of wafers is significantly reduced, and the productivity is increased.

The inventive device can be used not only for galvanizing of wafers but for galvanizing of any flat substrates.

Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is, therefore, not intended that the present invention be limited to the memberlosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A device for galvanizing of member-shaped substrates, comprising a base (1); an adapter (5) supported on the base (1) for supporting a to-be galvanized member-shaped substrate (2); an upper sealing ring for securing the to-be-galvanized member-shaped substrate (2) to the adapter (5) and provided at its opposite upper and lower ends with recesses for receiving respective O-rings (6, 7); an annular complementary member (10) located opposite the upper sealing ring (3) and having counter-recesses complementary to a recess formed in the lower end of the sealing ring (3) and in which a respective O-ring (7) is received, the annular complementary member (10) being mounted in the base (1) without any side clearance and sealing, together with the sealing ring (3), with the respective O-rings (6, 7) being received in respective recess, an electrolyte region; and a union nut (4) for securing an entire system of the device together

2. A galvanizing device according to claim 1, further comprising one of pneumatic means and hydraulic means for pressing the annular member (10) against the sealing ring (3).

3. A galvanizing device according to claim 2, further comprising double-side bellows (9) for supporting the annular member (10), and wherein the one of pneumatic means and hydraulic means includes a channel (14) formed in the bellows (9) for conducting one of pneumatic and hydraulic medium, respectively, for applying pressure to the annular member (10).

4. A galvanizing device according to claim 2, further comprising a flat flexible diaphragm (17) for supporting the annular member (10), and wherein the one of pneumatic means and hydraulic means includes means for conducting one of pneumatic medium and hydraulic medium against the diaphragm (17).

5. A galvanizing device according to claim 3, further comprising control means for controlling flow of the one of pneumatic medium and hydraulic medium toward the annular member (10) in accordance with a load applied to the O-rings (6, 7).

6. A galvanizing device according to claim 3, further comprising control means for controlling flow of the one of pneumatic medium and hydraulic medium toward the annular member (10) in accordance with a load applied to the O-rings (6, 7).

7. A galvanizing device according to claim 1, further comprising a buffer elastic support member (8, 12) for balancing a pressure applied to O-rings.

8. A galvanizing device according to claim 1, further comprising bellows means (9) for further sealing the electrolyte region.