GB2564894A

GB2564894A - System for chemical and/or electrolytic surface treatment

Info

Publication number: GB2564894A
Application number: GB1712067.6A
Authority: GB
Inventors: Gleissner Andreas; Knoll Oliver; Wimsberger Thomas; Ötzlinger Herbert
Original assignee: Semsysco GmbH
Current assignee: Semsysco GmbH
Priority date: 2017-07-27
Filing date: 2017-07-27
Publication date: 2019-01-30
Anticipated expiration: 2037-07-27
Also published as: TWI751817B; TW202014559A; TWI711726B; JP7229690B2; CN109306476A; GB201712067D0; JP2023062067A; TW201910562A; TWI678437B; JP2019052370A; GB2564894B; TW202120749A

Abstract

A system 10 for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid, a device for chemical and/or electrolytic surface treatment of a substrate in a process fluid, and a method for chemical and/or electrolytic surface treatment of a substrate in a process fluid are all described. The system 10 for surface treatment comprises a basin 11, a fluid passage 12, an expansion tank 13, and a control unit 14. The basin is configured for the surface treatment of the substrate in the process fluid. The fluid passage links the basin and the expansion tank. The expansion tank is configured to hold an expansion volume of the process fluid. The control unit and the fluid passage are configured to maintain a level of the process fluid in the basin at an essentially constant level.

Description

The invention relates to a system for chemical and/or electrolytic surface treatment of a substrate in a process fluid, a device for chemical and/or electrolytic surface treatment of a substrate in a process fluid, and a method for chemical and/or electrolytic surface treatment of a substrate in a process fluid.

BACKGROUND OF THE INVENTION

In the semiconductor industry, various processes can be used to deposit or remove materials on or from the surface of wafers.

For example, electrochemical deposition (ECD) or electrochemical mechanical deposition (ECMD) processes can be used to deposit conductors, such as copper, on previously patterned wafer surfaces to fabricate device interconnect structures.

Chemical mechanical polishing (CMP) is commonly used for a material removal step. Another technique, electropolishing or electroetching, can also be used to remove excess materials from the surface of the wafers.

Electrochemical (or electrochemical mechanical) deposition of materials on wafer surfaces or electrochemical (or electrochemical mechanical) removal of materials from the wafer surfaces are collectively called electrochemical processing. Electrochemical, chemical and/or electrolytic processing techniques may comprise electropolishing (or electroetching), electrochemical mechanical polishing (or electrochemical mechanical etching), electrochemical deposition and electrochemical mechanical deposition. All techniques utilize a process fluid.

Chemical and/or electrolytic surface treatment techniques involve the following steps. A substrate to be processed is attached to a substrate holder, immersed into an electrolytic process fluid and serves as a cathode. An electrode is immersed into the process fluid and serves as an anode. A direct current is applied to the process fluid and dissociates positively charged metal ions at the anode. The ions then migrate to the cathode, where they plate the substrate attached to the cathode.

One difficulty in such a process is that as the wafer is lowered into the process solution, gas bubbles may be trapped under the wafer. If the process is a deposition process for copper, for example, such bubbles prevent copper from depositing onto the bubblecontaining regions on the wafer surface, giving rise to un-plated or under-plated areas, which represent defects in the plated material. Such defects reduce the reliability of the interconnect structures. Similarly, in an electropolishing process, trapped bubbles retard material removal from the regions containing the bubbles, giving rise to non-uniformities and defects and cause reliability problems.

US 2004/182712 Al hereto discloses a pre-wetting method and system for preventing gas bubble formation on a selected region of a wafer surface as the surface is brought in contact with a process solution for an electrochemical process. During the process, the wafer surface is initially brought in proximity of the surface of the process solution. Next, a process solution flow is directed towards the selected region of the wafer surface for a predetermined time. In the following step, the selected region of the wafer surface is contacted with the process solution flow for the predetermined time to prevent bubble formation, and the wafer surface is immersed into the process solution for electrochemical processing.

However, such pre-wetting approach is not an optimum.

SUMMARY OF THE INVENTION

Hence, there may be a need to provide an improved system for chemical and/or electrolytic surface treatment of a substrate in a process fluid, which still allows a better and more uniform material deposition on the substrate.

The problem of the present invention is solved by the subject-matters of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the aspects of the invention described in the following apply also to the system for chemical and/or electrolytic surface treatment of a substrate in a process fluid, the device for chemical and/or electrolytic surface treatment of a substrate in a process fluid, and the method for chemical and/or electrolytic surface treatment of a substrate in a process fluid.

According to the present invention, a system for chemical and/or electrolytic surface treatment of a substrate in a process fluid is presented.

The chemical and/or electrolytic surface treatment may be any material deposition, galvanized coating, chemical or electrochemical etching, anodal oxidation, metal separation or the like.

The substrate may comprise a conductor plate, a semi-conductor substrate, a film substrate, an essentially plate-shaped, metal or metallized workpiece or the like. A surface of the surface to be treated may be at least partially masked or unmasked.

The system for chemical and/or electrolytic surface treatment comprises a basin, a fluid passage, an expansion tank, and a control unit.

The basin is configured for the chemical and/or electrolytic surface treatment of the substrate in the process fluid. In other words, it is the reservoir, in which the substrate is treated, e.g. coated. The basin may be a vertical plating chamber, in which the substrate may be vertically inserted.

The fluid passage links the basin and the expansion tank. It may be a connection or pipe between the basin and the expansion tank.

The expansion tank is configured to hold an expansion volume of the process fluid. It may be another reservoir arranged next to the basin. The expansion tank may have a smaller volume than the basin.

The control unit may be a processor. It may detect the level of the process fluid in the basin and/or the expansion tank. It may operate the process fluid to enter or exit the basin and/or the expansion tank.

The control unit and the fluid passage are configured to maintain a level of the process fluid in the basin essentially constant. The term “essentially constant” may be understood in that a height of the liquid process fluid in the basin remains at the same level independent of an external influence. The term “essentially constant” may be understood as in a range of 15 % more or less than exactly constant, preferably in a range of 10 % more or less than exactly constant, and more preferably in a range of 5 % more or less than exactly constant. The control unit and the fluid passage may also be configured to maintain a level of process fluid in the basin constant. The term “essentially constant” may be understood as less than 5 % more or less than exactly constant. The control unit and the fluid passage may also be configured to maintain a level of the process fluid in the basin constant in the meaning of exactly constant.

The system for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the invention allows preventing a drying of components of a device for chemical and/or electrolytic surface treatment, as e.g. a distribution body to be arranged in the basin. A drying may lead to a detrimental crystallization of particles of the process fluid. The distribution body may be a component configured to direct a flow of process fluid and/or electrical current to the substrate.

The system for chemical and/or electrolytic surface treatment according to the invention may further allow preventing an introduction of air into components of a device for chemical and/or electrolytic surface treatment, as e.g. the distribution body, an anode and/or an enclosure comprising the distribution body and/or the anode. An introduction of air may lead to a detrimental oxidation of particles of the process fluid and/or to a so-called bubble shielding of the substrate.

As a result, the system for chemical and/or electrolytic surface treatment according to the invention allows a homogenous liquid flow on the substrate surface, a targeted distribution of an electric field between the substrate and a counter electrode, and thereby an easier and more uniform material deposition on the substrate.

In an example, the substrate holder holds the substrate. The external influence, which could change the level of the process fluid in the basin, which is prevented here, may be an insertion and/or a removal of a substrate holder alone or holding one or two substrates (one substrate on each side of the substrate holder). In an example, the control unit is configured to maintain the level of the process fluid essentially constant when a substrate holder is removed from the basin. In an example, the fluid passage is configured to maintain the level of the process fluid essentially constant when the substrate holder is inserted into the basin. The substrate holder may displace a volume of e.g. 20 liters, while the expansion tank may have a volume of e.g. 30 liters.

The external influence, which could change the level of the process fluid in the basin, which is prevented here, may also be an evaporation of the process fluid, a flushing, a spilling, a failure or the like.

In an example, the system further comprises a pumping means configured to continuously circulate the process fluid between the basin and the expansion tank. The pumping means may be a pump. It may permanently pump the process fluid from the basin to the expansion tank and back.

In an example, the pumping means is configured to increase a pumping volume to balance the removal of the substrate holder. In other words, when an expansion volume has to be pumped from the basin to the expansion tank, this can be done by increasing the pumping volume per time, e.g. by increasing a motor speed. In contrast, the pumping means may also be configured to move the process fluid between the basin and the expansion tank only in case an expansion volume has to be moved to keep the level of the process fluid in the basin essentially constant.

In an example, the fluid passage links an overflow outlet of the basin with the expansion tank.

In an example, the control unit is configured to maintain the level of the process fluid above an uppermost portion of a distribution body to be arranged in the basin. The distribution body may be a component configured to direct a flow of process fluid and/or electrical current to the substrate. In another example, the control unit is configured to maintain the level of the process fluid essentially at a level of an uppermost portion of a distribution body to be arranged in the basin. Both possibilities allow preventing any damage of the distribution body by drying, an introduction of air or the like. In an example, the control unit is configured to prevent a drying of the distribution body to be arranged in the basin. In an example, the control unit is configured to prevent an introduction of air into the distribution body to be arranged in the basin.

In an example, the system further comprises a temperature control system configured to detect a temperature of the process fluid and to control a change of the temperature of the process fluid, e.g. by heating and/or cooling.

In an example, the system further comprises a composition control system configured to detect a chemical property of the process fluid and to control a change of the chemical property of the process fluid. The chemical property of the process fluid may be a composition, a pH value, an amount of an additive or the like. The change of the chemical property may be done by adding some component.

According to the present invention, also a device for chemical and/or electrolytic surface treatment of a substrate in a process fluid is presented. The device for chemical and/or electrolytic surface treatment comprises a system for chemical and/or electrolytic surface treatment of a substrate in a process fluid as described above and a substrate holder. The substrate holder is configured to hold the substrate. The substrate holder may be configured to hold one or two substrates (one substrate on each side of the substrate holder).

According to the present invention, also a method for chemical and/or electrolytic surface treatment of a substrate in a process fluid is presented. The method for chemical and/or electrolytic surface treatment comprises the following steps, not necessarily in this order:

a) guiding an expansion volume of the process fluid from a basin for chemical and/or electrolytic surface treatment of the substrate to an expansion tank, and

b) re-inserting the expansion volume of the process fluid from the expansion tank to the basin so that a level of the process fluid in the basin is maintained essentially constant.

In an example, the method for chemical and/or electrolytic surface treatment further comprises the following steps:

inserting a substrate holder into the basin correlating to step a), and removing the substrate holder from the basin correlating to step b). The substrate holder may hold one or two substrates (one substrate on each side of the substrate holder).

In an example, the process fluid is continuously circulated between the basin and the expansion tank.

In an example, the method further comprises a temperature control method, which is configured to detect a temperature of the process fluid and to control a change of the temperature of the process fluid, e.g. by heating and/or cooling.

In an example, the method further comprises a composition control method configured to detect a chemical property of the process fluid and to control a change of the chemical property of the process fluid. The chemical property of the process fluid may be a composition, a pH value, an amount of an additive or the like. The change of the chemical property may be done by adding some component.

As a result, the invention relates to a method for realizing locally defined liquid flows on approximately planar substrates for the purpose of a controllable material transport of the entire surface thereof, as well as a device for the constructive realization of the method according to the invention. Simultaneously, the invention allows the targeted distribution of an electric field on a conductive substrate surface.

Devices and methods are suitable, in particular, for the processing of structured semi-conductor substrates, conductor plates, and film substrates, but also for processing of the entire surface of planar metal and metallized substrates. Device and methods may also be used according to the invention for the production of large surface photoelectric panels for solar energy generation, or large-scale monitor panels.

It shall be understood that the system, the device, and the method for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the independent claims have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims. It shall be understood further that a preferred embodiment of the invention can also be any combination of the dependent claims with the respective independent claim.

These and other aspects of the present invention will become apparent from and be elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described in the following with reference to the accompanying drawings:

Figure 1 shows schematically and exemplarily an embodiment of a device for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the invention.

Figure 2 shows schematically and exemplarily an embodiment of a substrate holder holding two substrates.

Figure 3 shows schematically and exemplarily an embodiment of a system for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the invention.

Figure 4 shows schematically and exemplarily an embodiment of a system for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the invention.

Figure 5 shows basic steps of an example of a method for chemical and/or electrolytic surface treatment of a substrate in a process fluid according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Figures 1, 3 and 4 show schematically and exemplarily an embodiment of a device 100 for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid according to the invention. The device 100 for chemical and/or electrolytic surface treatment comprises a substrate holder 20 and a system 10 for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid.

The substrate holder 20 is shown in Figure 2 and configured to hold the substrate 30. The substrate holder 20 here holds two substrates, one substrate 30 on each side of the substrate holder 20. The substrate holder 20 may also be configured to hold only one substrate, which may be treated from one or both sides.

The system 10 for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid as shown in Figures 1, 3 and 4 produces targeted flow and current density patterns for a chemical and/or electrolytic surface treatment. It comprises two distribution bodies 21 submerged in a process fluid (not shown). Opposite of each distribution body 21 is a substrate 30 that is attached to a substrate holder 20. The surface of the substrate 30 is wetted by the process fluid. Two electrodes, here two anodes 22, are present, which each are located on a side of the distribution body 21 opposite of the substrate 30, and which are also bathed in the process fluid.

The distribution body 21 has at least one inlet opening 23 for the process fluid and at least one liquid passage ending at an outlet nozzle array (not shown) at a front face of the distribution body 21. The pumped process fluid flows through the outlet nozzles at a relatively high speed in the direction of the substrate 30 and carries out the desired chemical and/or electrolytic reaction at that location.

The substrate 30 may be an essentially plate-shaped workpiece for the production of electric or electronic components, which is mechanically fixed in a substrate holder 20, and the surface of which to be treated is bathed in the process fluid as the treatment medium coming from the distribution body 21. In a special case, the substrate 30 may be a masked or unmasked conductor plate, a semi-conductor substrate, or a film substrate, or even any metal or metallized workpiece having an approximately planar surface.

The distributor body may advantageously consist of plastic, in particularly advantageous manner of polypropylene, polyvinyl chloride, polyethylene, acrylic glass, i.e. polymethyl methacrylate, polytetrafluoroethylene, or another material that will not be decomposed by the process solution.

The anode 22 is attached in a rear region of the distribution body 21, in mechanical contact with, or spatially separated from, the distribution body 21 such that the electric current flow is carried out between the anode 22 and the substrate 30 acting as counter electrode within the process fluid. Depending on the surface treatment method used, the anode 22 may consist of a material that is insoluble in the process liquid, such as platinizized titanium, or otherwise a soluble material, such as for example, the metal to be galvanically separated.

Figures 3 and 4 show schematically and exemplarily an embodiment of the system 10 for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid according to the invention. The system 10 for chemical and/or electrolytic surface treatment comprises a basin 11, a fluid passage 12, an expansion tank 13, and a control unit 14. The substrate holder 20 with the substrate 30 are arranged in the basin 11 in Figure 3 and outside the basin 11 in Figure 4.

The basin 11 is configured for the chemical and/or electrolytic surface treatment of the substrate 30 in the process fluid and forms the reservoir, in which the substrate 30 is treated. The basin 11 is a vertical plating chamber, in which the substrate 30 (not shown) is vertically inserted.

The fluid passage 12 links the basin 11 and the expansion tank 13 in form of a pipe between the basin 11 and the expansion tank 13.

The expansion tank 13 holds an expansion volume of the process fluid and is arranged next to the basin 11. The expansion tank 13 has a smaller volume than the basin 11.

The control unit 14 is here a processor. It detects the level of the process fluid in the basin 11 and operates the process fluid to enter or exit the basin 11 and/or the expansion tank 13. It may therefore control a pumping means 15.

The control unit 14 and the fluid passage 12 maintain a level of the process fluid in the basin 11 essentially constant. The term “essentially constant” may be understood in that a height of the liquid process fluid in the basin 11 remains at the same level independent of an external influence.

The control unit 14 maintains the level of the process fluid essentially constant when the substrate holder 20 without or with one or two substrates 30 is removed from the basin 11 (Figure 4) and when the substrate holder 20 is inserted into the basin 11 (Figure 3). A level L of the process fluid in the expansion tank 13 therefore decreases from Figure 3 to Figure 4.

The system 10 further comprises a pumping means 15 to continuously circulate the process fluid between the basin 11 and the expansion tank 13, which means from the basin 11 to the expansion tank 13 and back. The pumping means 15 may increase a pumping volume to balance the removal of the substrate holder 20.

The fluid passage 12 links an overflow outlet 16 of the basin 11 with the expansion tank 13.

The control unit 14 maintains the level of the process fluid above an uppermost portion of a distribution body 21 arranged in the basin 11. The control unit 14 may also maintain the level of the process fluid essentially at a level of the uppermost portion of the distribution body 21 arranged in the basin 11. Both possibilities allow preventing any damage of the distribution body 21 by drying, an introduction of air or the like. Thereby, the control unit 14 prevents a drying of the distribution body 21 in the basin 11. Further, the control unit 14 prevents an introduction of air into the distribution body 21.

The system 10 further comprises a temperature control system 17 to detect a temperature of the process fluid and to control a change of the temperature of the process fluid, e.g. by heating and/or cooling.

The system 10 further comprises a composition control system 18 to detect a chemical property of the process fluid and to control a change of the chemical property of the process fluid. The chemical property of the process fluid may be a composition, a pH value, an amount of an additive or the like. The change of the chemical property may be done by adding some component.

The system 10 for chemical and/or electrolytic surface treatment of the substrate 30 in the process fluid according to the invention allows preventing a drying of components of a device 100 for chemical and/or electrolytic surface treatment. It may further allow preventing an introduction of air into components of a device 100 for chemical and/or electrolytic surface treatment. As a result, the system 10 for chemical and/or electrolytic surface treatment according to the invention allows a homogenous liquid flow on the substrate surface, a targeted distribution of an electric field between the substrate 30 and a counter electrode, and thereby an easier and more uniform material deposition on the substrate 30.

Figure 5 shows a schematic overview of steps of a method for chemical and/or electrolytic surface treatment of a substrate 30 in a process fluid. The method for chemical and/or electrolytic surface treatment comprises the following steps:

In a first step SI, guiding an expansion volume of the process fluid from a basin 11 for chemical and/or electrolytic surface treatment of the substrate 30 to an expansion tank 13.

In a second step S2, re-inserting the expansion volume of the process fluid from the expansion tank 13 to the basin 11 so that a level of the process fluid in the basin 11 is maintained essentially constant.

The method for chemical and/or electrolytic surface treatment may further comprises an inserting a substrate holder 20 into the basin 11 correlating to step SI and a removing the substrate holder 20 from the basin 11 correlating to step S2.

The substrate holder 20 may hold one or two substrates (one substrate 30 on each side of the substrate holder 20 s shown in Figure 2).

It has to be noted that embodiments of the invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method type claims whereas other embodiments are described with reference to the device type claims. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters is considered to be disclosed with this application. However, all features can be combined providing synergetic effects that are more than the simple summation of the features.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfil the functions of several items re-cited in the claims. The mere fact that certain measures are re-cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A system (10) for chemical and/or electrolytic surface treatment of a substrate (30) in a process fluid, comprising:

a basin (11), a fluid passage (12), an expansion tank (13), and a control unit (14), wherein the basin (11) is configured for the chemical and/or electrolytic surface treatment of the substrate (30) in the process fluid, wherein the fluid passage (12) links the basin (11) and the expansion tank (13), wherein the expansion tank (13) is configured to hold an expansion volume of the process fluid, and wherein the control unit (14) and the fluid passage (12) are configured to maintain a level of the process fluid in the basin (11) essentially constant.

2. System (10) according to claim 1, further comprising a pumping means (15) configured to continuously circulate the process fluid between the basin (11) and the expansion tank (13).

3. System (10) according to one of the preceding claims, wherein the control unit (14) is configured to maintain the level of the process fluid essentially constant when a substrate holder (20) is removed from the basin (11).

4. System (10) according to claims 2 and 3, wherein the pumping means (15) is configured to increase a pumping volume to balance the removal of the substrate holder (20).

5. System (10) according to one of the preceding claims, wherein the fluid passage (12) is configured to maintain the level of the process fluid essentially constant when the substrate holder (20) is inserted into the basin (11).

6. System (10) according to one of the preceding claims, wherein the fluid passage (12) links an overflow outlet (16) of the basin (11) with the expansion tank (13).

7. System (10) according to one of the claims 3 to 6, wherein the substrate holder (20) holds the substrate (30).

8. System (10) according to one of the preceding claims, wherein the control unit (14) is configured to maintain the level of the process fluid above an uppermost portion of a distribution body (21) to be arranged in the basin (11).

9. System (10) according to one of the claims 1 to 7, wherein the control unit (14) is configured to maintain the level of the process fluid essentially at a level of an uppermost portion of a distribution body (21) to be arranged in the basin (11).

10. System (10) according to one of the preceding claims, further comprising a temperature control system (17) configured to detect a temperature of the process fluid and to control a change of the temperature of the process fluid.

11. System (10) according to one of the preceding claims, further comprising a composition control system (18) configured to detect a chemical property of the process fluid and to control a change of the chemical property of the process fluid.

12. System (10) according to one of the preceding claims, wherein the control unit (14) is configured to prevent a drying of the distribution body (21) to be arranged in the basin (11).

13. System (10) according to one of the preceding claims, wherein the control unit (14) is configured to prevent an introduction of air into the distribution body (21) and/or an anode (22) to be arranged in the basin (11).

14. A device (100) for chemical and/or electrolytic surface treatment of a substrate (30) in a process fluid, comprising:

a system (10) according to one of the proceeding claims, and a substrate holder (20), wherein the substrate holder (20) is configured to hold the substrate (30).

15. A method for chemical and/or electrolytic surface treatment of a substrate (30) in a process fluid, comprising the following steps:

a) guiding an expansion volume of the process fluid from a basin (11) for chemical and/or electrolytic surface treatment of the substrate (30) to an expansion tank (13), and

b) re-inserting the expansion volume of the process fluid from the expansion tank (13) to the basin (11), so that a level of the process fluid in the basin (11) is maintained essentially constant.

16. Method according to the preceding claim, further comprising the following steps:

inserting a substrate holder (20) into the basin (11) correlating to step a), and removing the substrate holder (20) from the basin (11) correlating to step b).

17. Method according to one of the preceding claims, wherein the process fluid is continuously circulated between the basin (11) and the expansion tank (13).

Amendments to the claims have been filed as follows: