Method and apparatus for estimating the reduction efficiency of oxide layers on wafers by color sensing

Abstract

The present invention relates to a method and apparatus for estimating the reduction efficiency of an oxide layer on a wafer by color sensing. A method for preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation is disclosed. In some embodiments, the method may include: exposing a surface of the semiconductor substrate to a plasma to treat the surface by reducing a metal oxide on the surface, and thereafter measuring a color signal from the surface after the plasma contact, the color signal having one or more color components. The method may then further include: estimating the degree of oxide reduction due to the plasma treatment based on the color signal after the plasma contact. In some embodiments, the degree of oxide reduction due to the plasma treatment is estimated based on the b* component of the color signal after the plasma contact. A plasma processing apparatus that can implement the aforementioned method is also disclosed.

Description

[0001] This application is a divisional application of the invention patent application with application number 201710058368.7, application date January 23, 2017, the applicant is Rum Research Company, and the invention name is "Method and device for estimating the reduction efficiency of the oxide layer on the chip through color sensing". Technical Field

[0002] The present disclosure relates to the manufacture of electronic devices, electroplating of semiconductor substrates, electroplating systems and apparatus with integrated and / or in-situ metrology systems for inspecting semiconductor wafers during processing, and methods of performing metrology and inspection of semiconductor wafers during processing. Background Art

[0003] The manufacture of integrated circuits typically involves one or more steps of electroplating a conductive metal layer onto the surface of a semiconductor wafer. For example, in some integrated circuit (IC) manufacturing procedures, an electroplating operation may be used to fill various features formed in the surface of a semiconductor wafer with metal, such as grooves and through-holes that serve as conductive paths between various circuit elements. The electroplated metal is typically copper, but other metals may be suitable and / or advantageous, including ruthenium, palladium, iridium, rhodium, osmium, cobalt, nickel, gold, silver, and aluminum, depending on the IC design. In some embodiments, alloys of these metals may be suitable and / or advantageous.

[0004] In a typical electroplating operation, the surface of the wafer is exposed to a plating bath containing dissolved ions of the metal to be plated, and an electrical circuit is formed between an electrode in the plating bath (which serves as an anode) and the surface of the wafer (which serves as a cathode). Current flowing through this circuit when an applied voltage is applied causes electrons to flow to the cathode surface and reduce dissolved metal ions in its vicinity, resulting in the electroplating of neutral elemental metal in the solution onto the surface of the wafer.

[0005] However, in order to realize the circuit and in order to make the electrochemical reduction of dissolved metal ions occur, the surface of the wafer (used as the cathode of the circuit) must be relatively conductive at least to a certain extent. Therefore, since the exposed surface of the semiconductor wafer is generally substantially non-conductive, the actual electroplating step in the electroplating operation is generally preceded by the deposition of a conductive seed layer, which provides the necessary conductive surface. The deposition of the seed layer can be completed by any feasible method of depositing the seed material. Suitable methods may include, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), conformal film deposition (CFD), atomic layer deposition (ALD), etc. Typically, seed layer deposition and electroplating are followed by an edge bevel removal (EBR) operation, which removes the seed metal deposited at the edge of the wafer by applying a thin viscous flow of an etchant solution on the edge of the wafer, which is not expected to be present at the edge of the wafer.

[0006] However, typically, after the seed layer is deposited, the wafer is removed from the vacuum and exposed to the clean room ambient air. In some cases, there may be a queue time ranging from a few minutes to a few hours before the wafer is plated. The delay time and the associated exposure to ambient air can lead to oxidation of the seed layer - commonly referred to as "seed aging". Such a substantially non-conductive oxide layer produced by seed aging can reduce the efficiency of electroplating or even prevent electroplating from occurring. In addition, the surface wetting characteristics of the wafer may also change, which also contributes to defects on the wafer. Due to too much pre-plating seed aging, post-plating pores and depressions have been seen on patterned wafers, which result in useless IC devices and therefore negatively affect the overall wafer yield. In addition, it is observed that, for example, in lower technology nodes (e.g., below 22nm), the seed aging effect worsens, where the seed layer is typically very thin, such as 50 angstroms or less in some cases. Seed dissolution and reduction in current density can also be seen, where thinner seeds in localized areas go deeper into vias and trenches with higher, denser pattern density, also leading to defects after the plated wafer. Accordingly, methods and apparatus for processing oxide layer reduction and / or removal have been developed, and further improvements to these methods and apparatus are disclosed herein. Summary of the invention

[0007] Disclosed herein is a method for preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation. In some embodiments, the method may include: exposing a surface of the semiconductor substrate to a plasma to treat the surface by reducing a metal oxide on the surface, after which a color signal after plasma contact is measured from the surface, the color signal having one or more color components. The method may then further include: estimating the extent of oxide reduction due to the plasma treatment based on the color signal after plasma contact. In some embodiments, the extent of oxide reduction due to the plasma treatment is estimated based on a b* component of the color signal after plasma contact.

[0008] Also disclosed is a plasma processing apparatus for reducing metal oxides present on the surface of a metal seed layer of a semiconductor substrate prepared for a subsequent electroplating operation. In some embodiments, the apparatus may include: a processing chamber having at least one processing station within the processing chamber; a substrate holder configured to hold a substrate at the processing station; a plasma generator configured to generate plasma within the processing chamber and / or provide plasma to the processing chamber; and a color sensor configured to measure a color signal from the substrate, the color signal having one or more color components. The apparatus may further include: a controller having non-transitory computer-readable instructions for operating the apparatus and its various components. In some embodiments, the controller may include instructions for the following operations: operating the plasma generator to generate plasma within the processing chamber and / or provide plasma to the processing chamber so that the plasma contacts the surface of the substrate at the processing station to treat the surface by reducing the metal oxides on the surface. In some embodiments, instructions for the following operations may be included: after the plasma contacts the surface of the substrate, operating the color sensor to measure a post-plasma contact color signal from the surface, the color signal having one or more color components. In some embodiments, instructions for the following operations may be included: estimating the extent of oxide reduction due to the plasma treatment based on the color signal after the plasma contact. In some embodiments, the color sensor of the device can be positioned and / or configured to measure the color signal from the substrate when the substrate is located at the processing station. In some embodiments, the device can also include: a load lock configured to provide a substrate access to the processing chamber; and the color sensor can be positioned and / or configured to measure the color signal from the substrate when the substrate is located in the load lock.

[0009] Specifically, some aspects of the present invention can be described as follows:

[0010] 1. A method for preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation, the method comprising:

[0011] - contacting the surface of the semiconductor substrate with a plasma to treat the surface by reducing metal oxides on the surface;

[0012] - measuring a post-plasma contact color signal from the surface after contact with the plasma, the color signal having one or more color components; and

[0013] - estimating the extent of reduction of the oxide due to the plasma treatment based on the color signal after the plasma exposure.

[0014] 2. The method of clause 1, wherein the extent of reduction of the oxide due to the plasma treatment is estimated based on a b* component of a color signal after the plasma exposure.

[0015] 3. The method of clause 1, wherein estimating the extent of reduction of the oxide due to the plasma treatment comprises:

[0016] - comparing the color signal after said plasma contact with one or more reference color signals.

[0017] 4. A method according to clause 3, wherein the comparison is based on the b* component of the color signal.

[0018] 5. The method of clause 1, wherein estimating the extent of reduction of the oxide due to the plasma treatment comprises:

[0019] - calculating one or more metrics, each of said metrics being indicative of a difference between said post-plasma contact color signal and a reference color signal from a set of one or more reference color signals.

[0020] 6. The method of clause 5, wherein each metric is monotonically related to the absolute value of the difference between the b* component of the post-plasma contact color signal and the b* component of a reference color signal.

[0021] 7. The method according to any one of clauses 1 to 6, further comprising:

[0022] - measuring a pre-plasma contact color signal from the surface prior to contact with the plasma, the color signal having one or more color components; and wherein estimating the extent of reduction of the oxide due to the plasma treatment comprises:

[0023] - Comparing the color signal before the plasma contact and the color signal after the plasma contact.

[0024] 8. The method of clause 7, wherein the comparison is based on a b* component of the color signal.

[0025] 9. The method of clause 7, wherein estimating the extent of reduction of the oxide due to the plasma treatment comprises:

[0026] - calculating a metric indicative of a difference between a color signal before said plasma contact and a color signal after said plasma contact.

[0027] 10. The method of clause 9, wherein the metric is monotonically related to the absolute value of the difference between the b* component of the color signal before the plasma contact and the b* component of the color signal after the plasma contact.

[0028] 11. The method of any one of clauses 1-6, wherein the plasma comprises hydrogen radicals.

[0029] 12. The method of any one of clauses 1 to 6, wherein the metal is copper.

[0030] 13. The method according to any one of clauses 1 to 6, wherein the metal is cobalt.

[0031] 14. The method of any of clauses 1-6, wherein measuring the post-plasma contact color signal is performed using a color sensor located approximately 0.1 inches to 5 inches from the substrate surface during the measuring.

[0032] 15. The method of clause 14, wherein measuring the post-plasma contact color signal is performed using a color sensor located approximately 0.4 inches to 1 inch from the substrate surface during the measuring.

[0033] 16. A plasma processing apparatus for reducing metal oxides present on the surface of a metal seed layer of a semiconductor substrate in preparation for a subsequent electroplating operation, the apparatus comprising:

[0034] - a processing chamber, within which there is at least one processing station;

[0035] - a substrate holder configured to hold a substrate at the processing station;

[0036] - a plasma generator configured to generate plasma within the process chamber and / or to provide the plasma to the process chamber;

[0037] - a color sensor configured to measure a color signal from the substrate, the color signal having one or more color components; and

[0038] - a controller having non-transitory computer readable instructions for:

[0039] - operating the plasma generator to generate plasma within the processing chamber and / or to provide the plasma to the processing chamber such that the plasma contacts a surface of a substrate at the processing station to process the surface by reducing a metal oxide on the surface;

[0040] - after the plasma contacts a surface of the substrate, operating the color sensor to measure a post-plasma contact color signal from the surface, the color signal having one or more color components; and

[0041] - estimating the extent of reduction of the oxide due to the plasma treatment based on the color signal after the plasma exposure.

[0042] 17. The apparatus of clause 16, wherein the color sensor is positioned and / or configured to measure the color signal from the substrate while the substrate is located at the processing station.

[0043] 18. The apparatus according to clause 16, further comprising:

[0044] - a load lock configured to provide substrate access to the process chamber; and

[0045] Wherein the color sensor is positioned and / or configured to measure the color signal from the substrate while the substrate is within the load lock.

[0046] 19. Apparatus according to any of clauses 16-18, wherein the colour sensor is configured to measure a colour signal having a b* colour component.

[0047] 20. The apparatus of clause 19, wherein estimating the extent of reduction of the oxide due to the plasma treatment is based on the b* component of the color signal after the plasma exposure.

[0048] 21. Apparatus according to any of clauses 16-18, wherein the plasma generator is remote from the processing chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1A is a flow chart of a method of preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation, which includes measuring at least one color signal.

[0050] Figure 1B is a flow chart of another method of preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation, which includes measuring at least two color signals.

[0051] Figure 2A three-color component color space using "a*," "b*," and "L*" color components is schematically shown.

[0052] Figure 3 A more detailed flow chart is provided to illustrate an electroplating method including plasma pretreatment and Figure 1A and 1B The operation shown is similar to that used to estimate the extent of oxide reduction in pretreatment.

[0053] Figure 4 A cross-sectional schematic diagram of an example of a plasma processing apparatus is shown.

[0054] Figure 5A A multi-station plasma processing apparatus having four processing stations is schematically shown.

[0055] Figure 5B (i) shows a schematic diagram of a load lock of a plasma processing apparatus in which a color sensor is installed.

[0056] Figure 5B (ii) shows a vertical cross-sectional view showing the positioning of the color sensor within the load lock (eg Figure 5B (indicated by the dashed line 505 in (i)).

[0057] Figure 5B (iii) shows a schematic vertical cross-section of the optical fiber head showing the color sensor in detail (enlarged, as shown in FIG. Figure 5B (shown as dashed oval 506 in (ii)).

[0058] Fig. 6A An exemplary flow chart illustrating a method of processing a substrate having a metal seed layer is shown.

[0059] Figure 6B An exemplary flow chart illustrating another method of processing a substrate having a metal seed layer is shown.

[0060] Figures 7A-7D An example of a cross-sectional schematic diagram illustrating various stages of processing a substrate having a metal seed layer using a plasma processing apparatus is shown.

[0061] Figure 8 Results of b* color component measurements for six wafers having a 200 angstrom oxide layer before and after plasma pretreatment are shown.

[0062] Fig.9A The effect of H2 plasma treatment on the L* color component is shown.

[0063] Fig. 9B The effect of H2 plasma treatment on the a* color component is shown.

[0064] Fig. 9C The effect of H2 plasma treatment on the b* color component is shown.

[0065] Fig.10 (a) shows the value of the b* color component as a function of time during a "multi-layer recipe" where the wafer passes through the outbound load lock twice.

[0066] Fig.10 (b) shows the Fig.10 (a) Close-up replot of a portion of the data.

[0067] Fig.11A Plotted are values ​​of the b* color component measured from six wafers (each having a 200 angstrom oxide layer) that have been plasma treated at 250°C for six different durations.

[0068] Fig. 11B Plotted are values ​​of the b* color component measured from 5 wafers (each having a 200 angstrom oxide layer) that have been plasma treated at 75°C for 5 different durations. DETAILED DESCRIPTION

[0069] In the following disclosure, many specific embodiments are described to provide a thorough understanding of the inventive concepts disclosed herein. However, it should be understood by those skilled in the art that the inventive concepts disclosed herein can be practiced in many cases with or without some of these specific details (such as by replacing optional elements or steps, or omitting certain elements or steps), while remaining within the scope and spirit of the inventive concepts disclosed herein. In addition, in the case where certain processes, processes, operations, steps, elements, modules, components and / or systems are known to those skilled in the art, it may not be necessary to describe in as much detail as possible in this article, so that the important aspects of the disclosed inventive concepts will not be unnecessarily blurred.

[0070] Oxidation of the seed layer

[0071] The metal seed layer will readily react with oxygen or water vapor in the air and oxidize from pure metal to a mixed film of metal oxide and buried pure metal. Although oxidation under ambient conditions may be limited to a thin surface layer of some metals, this thin layer may represent a significant portion or possibly the entire thickness of the thin seed layer used in current technology nodes. Technology nodes such as the 4×nm node, 3×nm node, 2×nm node, and 1×nm node, as well as nodes less than 10nm, may require a relatively thin seed layer. The aspect ratio of vias and trenches in technology nodes requiring relatively thin metal layers may be about 5:1 or greater. In such technology nodes, the average thickness of the metal seed layer may therefore be less than about 100 nm. In some implementations, the average thickness of the metal seed layer can be less than about

[0072] The metal used for the seed or barrier layer is converted into a metal oxide (MO x ), but the exact reaction mechanism between the metal surface (M) and ambient oxygen or water vapor can vary depending on the nature and oxidation state.

[0073] Reaction 1: 2M (s) +O 2(g) →2MO x(s)

[0074] Reaction 2: 2M (s) +H2O (g) →M2O x +H 2(g)

[0075] For example, it is known that copper seeds deposited on a substrate rapidly form copper oxide when exposed to air. The copper oxide film can form about 100% copper on top of the underlying copper metal. and at most As the metal seed layer becomes thinner, oxidation to form metal oxides under ambient conditions poses a major technical challenge.

[0076] As mentioned above, converting pure metal seeds to metal oxides can be problematic. This is true not only in current copper damascene processes, but also for electrodeposition processes using other conductive metals (e.g., ruthenium, cobalt, silver, aluminum, and alloys of these metals). First, oxidized surfaces are difficult to plate. On the one hand, the conductivity of the oxidized surface is not as good as that of the bare seed metal, which tends to suppress the plating rate. However, the surface may not be uniformly oxidized, making the plating uneven (because the plating rate depends on the surface conductivity) and slow. In addition, plating bath additives interact differently with metal oxides relative to pure metals, resulting in further uneven plating rates.

[0077] Second, as a result of oxidation, pores may form in the metal seed layer, which may render portions of the seed layer unavailable to support electroplating. Porosity may form during exposure to corrosive plating solutions due to dissolution of metal oxides. Porosity may also form on the surface due to uneven plating. Additionally, plating the bulk metal on an oxidized surface may result in adhesion or delamination problems, which may further result in porosity after subsequent processing steps such as chemical mechanical planarization (CMP). Porosity resulting from etching, uneven plating, delamination, or other processes may render the metal seed layer discontinuous and unable to support electroplating. In fact, because modern damascene metal seed layers are relatively thin, e.g., about 100 Å (as described), pores may form on the surface. or thinner, so even a small amount of oxidation may consume the entire thickness of the seed layer.

[0078] Third, and more generally, metal oxide formation is sometimes believed to cause problems with other substrate processing operations after electroplating. For example, metal oxide formation is sometimes observed to hinder the deposition of a capping layer after electrodeposition. In some cases, this may be due to the metal oxide layer effectively limiting the adhesion of the capping layer.

[0079] It may be difficult to avoid forming metal oxides on the seed layer after the seed layer has been deposited but before the main electroplating operation. Various intermediate processing steps that expose the seed layer to oxygen or water vapor under ambient conditions can be performed. For example, one or more rinsing steps (e.g., with deionized water) can be performed after the PVD method of depositing the metal seed layer, and then a subsequent drying step is performed before the main electrodeposition operation. The rinsing step can be limited to, for example, a time of about 1 to 10 seconds, but longer or shorter times can be used. Subsequent drying can be between about 20 and 40 seconds, but the drying step may require longer or shorter times. During these steps, the metal seed layer will be exposed to ambient conditions, and oxidation of the seed layer will occur.

[0080] Even in the absence of specific intermediate steps (such as rinsing and drying), seed layer deposition (e.g., by PVD) is typically performed in a processing chamber different from the electroplating pool used for electrodeposition. Therefore, there are often vacuum interruptions and wafer transfers between these processing modules, during which the seed layer may be exposed to ambient conditions, which may also cause the seed layer to oxidize. In some cases, the duration of this exposure can be anywhere between about 1 minute and 4 hours, or more particularly between about 15 minutes and 1 hour. Note that various suitable methods and devices for electroplating / deposition / filling are described in U.S. Patent No. 6,793,796 (Agent File No. NOVLP073), filed on February 28, 2001, the entire contents of which are incorporated herein by reference for all purposes. (The reference describes at least four stages of the electroplating / deposition / filling process, and discloses a controlled current density method for each stage to optimize the filling of relatively small embedded features)

[0081] Plasma treatment to remedy oxidation of the seed layer

[0082] Due to various factors that may lead to oxidation of the metal seed layer in the intermediate stages between the deposition of the seed layer and the subsequent bulk electroplating, there is a great need for effective recipes for reducing metal oxides after the seed layer is deposited. One approach is to pre-treat the surface of the substrate (prior to bulk electroplating) by contacting the surface of the substrate with a plasma that includes a reducing agent, which thereby serves to reduce the metal oxide formed on the surface of the substrate. The reducing plasma used in this plasma pre-treatment can be formed within the reaction chamber itself (the vacuum chamber that holds the substrate for pre-treatment), or the plasma source can be remote from the processing chamber (i.e., a "remote plasma" is formed and introduced into the processing chamber to contact and treat the substrate surface), although subsequent modifications may also be made once it enters the reaction chamber (e.g., ion filtering, so that free radicals primarily contact the substrate, etc.).

[0083] Such methods and apparatus for performing such electroplating pretreatment using a reducing plasma are described in detail in U.S. Patent Application No. 14 / 086,770, filed on November 21, 2011, entitled “METHOD AND APPARATUS FOR REMOTEPLASMA TREATMENT FOR REDUCING METAL OXIDES ON A METAL SEED LAYER,” (hereinafter referred to as the “'770 Application”), now published as U.S. Patent Publication No. 2014 / 0256128, which is incorporated herein by reference in its entirety for all purposes. As disclosed in the '770 Application, according to embodiments, the reducing gas species used to form the reducing plasma may be hydrogen (H2), ammonia (NH3), carbon monoxide (CO), diborane (B2H6), sulfite compounds, carbon and / or hydrocarbons, phosphites and / or hydrazine (N2H4), etc., and the excited reducing species in the plasma may be ions or radicals of the reducing gas, such as H*, NH2*, or N2H3*.

[0084] Reaction 3 shows an example of a reducing gas species (e.g., hydrogen) being decomposed into hydrogen radicals. Reaction 4 shows that the hydrogen radicals react with the metal oxide surface to convert the metal oxide into a metal. For undecomposed hydrogen molecules or hydrogen radicals that recombine to form hydrogen molecules, the hydrogen molecules can still be used as a reducing agent for converting the metal oxide into a metal, as shown in Reaction 5.

[0085] Reaction 3: H2 → 2H *

[0086] Reaction 4: (x)2H * +MO x →M+(x)H2O

[0087] Reaction 5: (x)H2+MO x →M+(x)H2O

[0088] As noted above, in some embodiments, the pretreatment plasma may also include ions of reducing gas species and other charged species, although it is often advantageous to filter out these charged species so that they do not reach the substrate and potentially damage the seed layer, as described in more detail below.

[0089] Qualitative / Quantitative Analysis of Plasma Pretreatment Performance

[0090] It has been found that the above-mentioned plasma pretreatment is very effective in reducing the effect of seed aging on subsequent bulk electroplating. However, it has been found that the characterization of the performance of the plasma pretreatment process in practical applications (in the field) is extremely challenging. In order to characterize the pretreatment performance, the wafer is usually oxidized in a controlled environment and then exposed to an oxide-reducing plasma in a pretreatment module. Sheet resistance measurements are performed before and after the plasma treatment, and the sheet resistance decrease usually characterizes the performance of the plasma pretreatment. Even though this technique is useful because it reveals the changes before and after the plasma pretreatment to some extent, it is still plagued by many problems in practical applications. Since the sheet resistance measurement is performed offline, there is a queue time between the plasma pretreatment and the offline measurement (which is performed at a separate dedicated metrology tool). Due to the queue time, the performance of the pretreatment (e.g., the degree of oxide removal) tends to be systematically underestimated. More importantly, random differences in the queue time may be a false indication of the variability of the pretreatment performance in practical applications. In some cases, if the queue time after the pretreatment is long enough, the pretreated wafer can regenerate almost all of the original oxide layer before the sheet resistance measurement is performed. Therefore, such off-line ex-situ techniques are not ideal for characterizing (and quantifying) the performance of a plasma pretreatment in practical applications where the queue time between pretreatment and measurement cannot be strictly controlled and / or even strictly predicted. What is desired (and disclosed herein) is an on-line in-situ measurement technique for quantifying oxide layer thickness in real time during or immediately after a plasma pretreatment, thereby providing a reliable characterization of plasma pretreatment performance. A plasma pretreatment module that implements such a technique is also desired (and disclosed herein).

[0091] Estimating oxide removal on wafers through color sensing

[0092] One mechanism for assessing the efficiency of oxide layer removal is to estimate the oxide layer thickness using a color sensor after and / or even during a plasma pretreatment operation. It has been found that analysis of a color signal measured from a wafer surface can be used as a basis for detecting the thickness of any remaining oxide layer during or after plasma pretreatment. In some embodiments, color signal measurement and analysis can accurately assess the performance of a plasma pretreatment module, for example, detecting module problems when they occur and helping to prevent wafer fragmentation in the field. Thus, a method of electroplating pretreatment of a substrate to prepare for subsequent electroplating may include reducing a metal oxide on a surface of a substrate by contacting the surface with a plasma, then measuring a color signal (from the surface), and estimating the extent of oxide reduction (due to the plasma treatment) based on the color signal.

[0093] The method for preparing a semiconductor substrate having a metal seed layer for a subsequent electroplating operation comprises: Figure 1A . As shown in the flowchart of . As shown, this method 100 begins with an operation 120 of contacting a surface of a semiconductor substrate with a plasma to treat the surface by reducing a metal oxide on the surface. Then, after contacting with the plasma, in operation 130, a post-plasma contact color signal is measured from the surface. This color signal can have one or more color components, as further described below. One or more color components can provide an indication of the thickness of the oxide layer. Therefore, in operation 140, the measured post-plasma contact color signal is used as a basis for estimating the extent of oxide reduction caused by the plasma treatment.

[0094] Note that the color signal measured from the substrate surface typically has multiple color components (although it may have only one color component). Once the color sensor has been adjusted and its settings optimized, it can detect small color variations on the wafer surface. In some embodiments, the color sensor outputs a color signal consisting of three color components. These may be RGB (red / green / blue) color values, but it is also feasible to define color components in some color space other than the RGB color space.

[0095] For example, in some embodiments, a set of L*, a*, and b* color components are measured and output by a color sensor; and these L*, a*, b* color components define an L* / a* / b* color space, such as Figure 2 As shown schematically in Figure 2 As shown, the "a*" color component represents the relative proportion of green to red in the color signal, the "b*" color component represents the relative proportion of blue to yellow in the color signal, and the "L*" color component indicates the overall brightness or luminosity of the color signal. Of course, although the values ​​of (a*, b*, L*) specify a position in this particular color space, one of ordinary skill in the art will recognize that other representations of color space are also possible, and that the actual physical color specified by a particular (a*, b*, L*) triplet in this color space will potentially be specified by different triplet values ​​of color components in different color spaces. In addition, one of ordinary skill in the art will readily appreciate that the inventive concepts disclosed herein are not limited to this particular color space representation with respect to the a*, b*, and L* components.

[0096] In principle, more than three color components can also be used in the measurement and analysis, for example 4, 5, 6, 7, 8, 9, 10 or 16 color components, or a plurality of color components ranging from 8 to 16 color components, or 16 to 32 color components, or 32 to 64 color components, or 64 to 128 color components, or 128 to 256 color components. If 3 or fewer color components are used, these color components can be selected as in Figure 2 Any combination of *a, *b or *L color components schematically shown in the figure, or a combination of other types of color components (whether one, two, three), such as a combination of RGB (red, green, blue) color components. It should also be noted that although the detection and reference color signals will generally include the same type and number of color components, this is not necessarily required. For example, by ignoring the additional color components, a metric indicating the difference between two color signals with different numbers of color components (or between the measured signal and the vector average) can still be calculated. In other embodiments, the components of the probe color signal can represent color space components that are different from the components of one or more reference color signals. If this is the case, various color space vector projection methods can be used to still formulate meaningful comparison metrics. Finally, it should also be noted that in the context of the present disclosure, in principle, a device that senses color and forms a color image, i.e., a color camera, can also be used. (Although, in general, commercially available color cameras are not as sensitive to slight color differences as commercially available color sensors. However, in principle, color cameras can also be effective, depending on the embodiment and the desired sensitivity.)

[0097] With respect to the L* / a* / b* color space, it has been found that the b* color component is very effective as a basis for determining the extent of oxide reduction (and / or removal) during or after a plasma pretreatment operation. This is due in part to differences in b* color values ​​attributable to the correlation of oxides to bare metal seeds, however (and not being limited to a particular theory), it is also due to the relative insensitivity of the b* color component to other unrelated artifacts, fluctuations, instabilities, etc. during color measurements. Some fluctuations and instabilities during color sensor measurements may be due to vibrations, changes in light intensity, changes in the gap between the sensor head and the wafer, the angle of the sensor head relative to the wafer, wafer swing, and changes in environmental conditions (including temperature, pressure, humidity, etc.). The color sensor may have its own internal light source, however, small changes in ambient light may interfere with the internal light source. For example, it has been found that the L* color component is very dependent on ambient light and is therefore not suitable as an indicator of wafer color changes due to oxide formation. It has been found that the other color components (the α* component) do not vary significantly between oxides and bare metal seeds.

[0098] Note that the b* color component is defined herein as a color component (e.g., a color component of a multi-component color signal) having a value that indicates the relative proportion of blue to yellow in the color signal (as described above with respect to Figure 2 ). There are many possible sets of color components that can define the color space measured by a particular color sensor. Some color sensors may measure only a single color component, which may be the b* color component. Some color sensors may measure more than 3 color components, one of which is the b* color component. Furthermore, even in sensors that measure 3 color components, there may be some variation in the color component measured and / or defined as the b* color component (the difference may be by design, or it may be due to unintentional manufacturing variations). However, in any of these cases, if the measured color component indicates a ratio of blue to yellow, it is included herein by being referred to as the b* color component.

[0099] In some embodiments, the color signal upon which the determination of oxide reduction efficiency is based is measured immediately after the plasma treatment is completed (or as soon thereafter as practicable). (How soon after may depend on the placement and / or mounting of the color sensor relative to where the plasma pretreatment occurs, although the idea is that it is close enough that the problems discussed above with respect to conventional off-line metrology are significantly reduced.) However, in other embodiments, the color signal upon which the determination of oxide reduction effectiveness is based may be measured during the plasma-based pretreatment oxide removal, or even multiple times throughout the course of the pretreatment.

[0100] Such measurements can be used for real-time fault detection during the pretreatment process so that problems can be corrected as quickly as possible and wafer losses are minimized. However, it is also noted that real-time oxide layer thickness measurements during pretreatment (especially if performed at various intervals during the pretreatment process) can be used as a basis for real-time adjustments to the pretreatment process itself (e.g., by adjusting the plasma intensity) or for endpoint determination (i.e., determining when it is advisable to stop the pretreatment process because all (or sufficient) oxide has been reduced and / or removed).

[0101] In any case, various processing analysis options are then possible in terms of processing this "post-plasma contact color signal" in order to measure oxide removal efficiency. For example, in some embodiments, the post-plasma contact color signal can be compared to one or more reference color signals. If the reference color signals indicate a particular level of oxide thickness (e.g., they are measured from a wafer with a known oxide layer thickness), then comparing the measured post-plasma contact color signal to these reference signals enables an estimate of the oxide layer thickness (and therefore the oxide removal efficiency).

[0102] In some embodiments, the comparison may entail identifying a reference color signal that is closest to the measured post-plasma contact color signal (the "probe" signal), and determining the oxide layer thickness to be the oxide layer thickness associated with that particular reference. If the comparison is based on a single color component, such as b* (or a single color band, such as 650 nm ± some Δλ), then the "closest" reference simply means that the value of its color component differs the least from the probe signal. If the comparison is based on multiple color components, then the "closest" reference is the one whose color component vector differs the least from the probe, i.e., it has the smallest value.

[0103]

[0104] where c i is the i-th component of the probe (measured color signal after plasma exposure) and the reference color signal, and N is the number of color signal components (as readily understood by one of ordinary skill in the art).

[0105] Of course, a differential metric that includes a scaled version of the magnitude of the vector difference will work similarly (e.g., the scaling may result from unit conversions), which will be various monotonic functions of the magnitude of the vector difference. One of ordinary skill in the art will readily appreciate that the particular functional form of the metric is not critical, so long as it results in a value that indicates the difference between the probe and reference color signals. The mathematical function representing the comparison metric can be implemented as an analytical function of the color signal, which can be implemented in a lookup table, or it can potentially be implemented using some other computational approach (e.g., a hybrid of analytical function evaluation and table lookup).

[0106] Since the b* color component is determined to be a good indicator of the thickness of the oxide layer, in a preferred embodiment, the b* component of the measured color signal (probe) after plasma exposure is compared to the b* component of the reference color signal. Thus, analysis based on the b* color component may involve calculating a set of metrics, each of which is monotonically related to the absolute value of the difference between the b* component of the color signal after plasma exposure and the b* component of the reference color signal (corresponding to an oxide layer of known thickness).

[0107] In more complex embodiments, the oxide layer thickness can be determined by interpolating between multiple reference color signals (corresponding to known oxide layer thicknesses). In some embodiments, multiple sets of color signals measured from multiple sets of reference wafers with known oxide layer thicknesses can be used to generate a functional relationship between the color signal and the oxide layer thickness, and the relationship can be used to estimate the oxide layer thickness of the test wafer (and thereby the efficiency of the plasma pretreatment process) based on the color signal measured from the test wafer surface. This functional relationship between the oxide layer thickness and the color signal can be linear, or approximately linear, or nonlinear, depending on the actual situation. Of course, the functional relationship will never be exact, but the best fitting functional relationship can be selected or determined from one or more experimental functional forms that fit a given data set (i.e., the measured values ​​of the color signal from the reference wafer with a known oxide layer thickness). As will be readily appreciated by those skilled in the art, the best fit will assume that one or more parameters associated with the functional form (e.g., if the functional relationship is assumed to be linear, then the slope and intercept of the line) establish values. Of course, a person skilled in the art will also understand that once the functional relationship between the color signal and the oxide thickness is determined (whether it is linear, nonlinear, etc.), the function can be applied to the measured color signal through analytical function evaluation, lookup table, etc. to calculate the approximate seed layer thickness.

[0108] Another set of color signal processing options can be used to analyze the pretreatment efficiency based on a comparison of one or more color signals measured after plasma exposure with one or more color signals measured before plasma pretreatment. Figure 1B As shown in the flowchart of FIG. 1 , the method 105 begins with operation 110, in which a pre-plasma contact color signal from a surface of a semiconductor substrate is measured before the surface of the semiconductor substrate is contacted with plasma. This is followed by operation 130, in which the surface of the substrate is contacted with plasma to treat the surface by reducing metal oxides on the surface. Then, as Figure 1A As in the method 100 of , after plasma contact, a post-plasma contact color signal is measured from the surface in operation 130. An estimate of the extent of oxide reduction due to the plasma treatment is then made in operation 145 by comparing the pre-plasma contact color signal with the post-plasma contact color signal.

[0109] Like the color signal (or signals) after plasma contact, the color signal before plasma contact can have one or more color components, and in particular can include a b* component. In some embodiments, the comparison of the color signal before plasma contact and the color signal after plasma contact can involve calculating a metric indicative of the difference between the color signal before plasma contact and the color signal after plasma contact. More specifically, if the b* component is used as the basis for the comparison, the metric will be monotonically related to the absolute value of the difference between the b* component of the color signal before plasma contact and the b* component of the color signal after plasma contact.

[0110] It has been found that color sensor measurements for evaluating plasma pretreatment efficiency can be used in a well-controlled vacuum environment (e.g., in a plasma processing chamber) as well as in an ambient environment (e.g., in the inbound and outbound load locks of the chamber, as described in more detail below). However, it has been found that color signal measurements work best when the head of the color sensor is close to the surface of the wafer, i.e., when there is only a small gap between the sensor and the wafer (described further below). This results in the most stable measurements with the best signal-to-noise ratio. Further details regarding the placement and / or mounting of the color sensor relative to the plasma processing chamber are described in more detail below.

[0111] Further details on plasma treatment of the seed layer

[0112] Figure 3 A more detailed flow chart is provided, which shows the electroplating method, which includes plasma pretreatment and Figure 1A and 1B The operations shown are similar to the operations for estimating the degree of oxide reduction in pretreatment. Method 300 begins at operation 305, where a metal seed layer (e.g., a thin copper layer) is deposited on a substrate. This provides a substrate having a metal seed layer on the electroplating surface of the substrate. The substrate may have a groove having an aspect ratio of height to width greater than about 3:1 or greater than about 5:1. At operation 310, the substrate is transferred (possibly under ambient conditions) to a processing chamber of, for example, a pretreatment module. In operation 315, the substrate is contacted with a reducing plasma (with ions and / or radical species of reducing gas species formed in or away from the processing chamber as described above) under vacuum or reduced pressure in the processing chamber. (The radicals and ion species can freely drift toward the substrate surface; in particular, the ions can be accelerated by, for example, an applied voltage bias between the showerhead and the substrate holder / pedestal). At operation 320, the treatment results in the reduction of the oxide on the metal seed layer and the formation of an unoxidized (or nearly so) metal surface. In some embodiments, as shown, the oxidized metal becomes an integrated film on the metal seed layer.

[0113] After the oxide reduction, the next two operations involve estimating the extent of the oxide reduction based on the color signal measurement. Specifically, in operation 322, the color signal after plasma contact is measured from the surface of the substrate. Then, again similar to Figure 1A and 1B , in operation 323, the extent of oxide reduction (completed in operation 320) is estimated based on the analysis of the color signal measured in operation 322. The method then proceeds to operation 325, where the substrate is transferred to an electroplating system (or an electroless plating system, other metal deposition system, or another pretreatment device) under ambient conditions or under an inert gas blanket. Although the metal oxide in the metal seed layer has been fully reduced by exposing the metal oxide surface to a reducing gas atmosphere, performing operation 325 may bring additional reoxidation challenges due to exposure to the surrounding environment. In some embodiments, techniques such as shortening the duration of the transfer or controlling the atmosphere during the transfer can be used to minimize exposure to ambient conditions. Additionally or alternatively, the transfer is performed in a controlled environment that is less oxidizing than ambient conditions. In order to control the atmosphere during the transfer, for example, the atmosphere can be substantially free of oxygen. The environment can be substantially inert and / or low pressure or vacuum. In some embodiments, the substrate can be transferred under an inert gas blanket. As described below, the transfer in operation 325 can occur from the plasma pretreatment chamber to the electroplating cell in the same apparatus or in two apparatuses (plasma treatment and electroplating) that are somewhat separate but still connected and integrated with one another, such that the substrate pretreated with the reducing plasma can be transferred to the electroplating cell under conditions that reduce, minimize, or eliminate exposure to oxidation that would result in its now substantially bare metal surface. In any case, once the substrate is pretreated with the reducing plasma, the substrate is transferred to the electroplating cell. Figure 3 If the method is transferred to operation 325 in the method, the method ends at operation 330, where the metal is finally electroplated onto the substrate surface, particularly in the preferred embodiment, onto a layer that is now a bare, substantially unoxidized metal seed layer on the substrate surface.

[0114] The pretreatment plasma may also generate and include UV radiation from the reducing gaseous species. In some embodiments, the UV photons may heat the surface of the substrate to activate the metal oxide surface for subsequent reduction, or in some cases, the UV photons may have sufficient energy to cause reduction of the metal oxide itself. Thus, in some embodiments, free radicals or ions of the reducing gaseous species, UV radiation from (neutrons, ions and / or free radicals of) the reducing gaseous species, or the reducing gaseous species themselves may reduce the metal oxide.

[0115] In addition, activated reducing gas species (ions, free radicals, etc.) can be combined with mixed gas species (e.g., relatively inert gas species). Examples of relatively inert gas species can include nitrogen (N2), helium (He), neon (Ne), krypton (Kr), xenon (Xe), radon (Rn), and argon (Ar). The flow rate of the reducing gas species used to form the reducing plasma can vary depending on the size of the wafer used for processing. For example, the flow rate can be between about 10 standard cubic centimeters per minute (sccm) and about 100,000 sccm to process a single 450 mm wafer. Other wafer sizes can also be used. For example, the flow rate of the reducing gas species used to form the plasma can be between about 500 sccm and about 30,000 sccm to process a single 300 mm wafer.

[0116] Temperature and pressure also affect the reactivity of the reducing plasma, although the temperature is generally kept below the temperature that causes agglomeration of the metal seed layer to be produced during exposure to the reducing gas atmosphere. As disclosed in the '770 application, suitable temperature and pressure can be as follows: the temperature of the reduction chamber can be relatively high so that the reducing gas species can dissociate into free radicals. For example, the reduction chamber can be anywhere between about 10°C and 500°C, such as between about 50°C and 250°C. Higher temperatures can be used to accelerate the metal oxide reduction reaction and shorten the duration of exposure to the reducing gas atmosphere. In some embodiments, the reduction chamber can have a relatively low pressure to substantially remove any oxygen from the reducing gas atmosphere, because minimizing the oxygen present in the atmosphere can reduce the impact of reoxidation. For example, the reduction chamber can be evacuated to a vacuum environment or a low pressure between about 0.1 Torr and about 50 Torr. The increased temperature and / or reduced temperature can also increase the reflux of metal atoms in the metal seed layer to produce a more uniform and continuous metal seed layer.

[0117] In some embodiments, as described in the '770 application, the substrate temperature can be controlled separately from the pretreatment chamber temperature to avoid or reduce damage to the metal seed layer. Depending on the type of metal in the metal seed layer, the metal can begin to agglomerate above a threshold temperature. In relatively thin seed layers, especially in seed layers with a thickness of less than about 100 angstroms, the effect of agglomeration is more significant. Agglomeration includes any continuous or semi-continuous metal seed layer agglomeration or beading into beads, bumps, islands or other agglomerates to form a discontinuous metal seed layer. This may cause the metal seed layer to peel off from the surface on which the metal seed layer is deposited, and may cause increased porosity during plating. For example, the temperature at which agglomeration begins to occur in copper is greater than about 100°C. Different agglomeration temperatures may be applicable to different metals.

[0118] In some embodiments, the substrate can be maintained at a temperature between about -10°C and about 150°C. In a copper seed layer, for example, the substrate can be maintained at a temperature between about 75°C and about 100°C. In a cobalt seed layer, the substrate can be maintained at a temperature greater than about 100°C. Therefore, a cooling system such as an actively cooled pedestal and / or an air flow cooling device in a pre-treatment chamber can be used to maintain a local area of ​​the substrate at a temperature below the agglomeration temperature. Depending on the embodiment, heat transfer can occur via conduction, convection, radiation, or a combination thereof. In some embodiments, a cooling fluid circulation loop can actively cool the substrate. Embodiments including cooling features are described in the following documents: U.S. Patent No. 7,327,948, issued on February 5, 2008 (Attorney Docket No. NOVLP127X1); U.S. Patent No. 7,941,039, issued on January 5, 2011 (Attorney Docket No. NOVLP127X3); U.S. Patent Application No. 11 / 751,584, filed on May 21, 2007 (Attorney Docket No. NOVLP127X2); U.S. Patent Application No. 13 / 370,579, filed on February 10, 2012 (Attorney Docket No. NOVLP127C1); U.S. Patent No. 8,137,465 issued on March 20, 2012 (Agent Docket No. NOVLP127); U.S. Patent Application No. 11 / 129,266 filed on May 12, 2005 (Agent Docket No. NOVLP361); U.S. Patent Application No. 11 / 546,189 filed on October 10, 2006 (Agent Docket No. NOVLP198) and U.S. Patent Application No. 12 / 749,170 filed on March 29, 2010 (Agent Docket No. NOVLP361D1); each of which is incorporated herein by reference in its entirety and for all purposes.

[0119] The duration of the plasma pretreatment may vary depending on other process parameters, as described in detail in the '770 application. For example, the exposure duration may be shortened by increasing the plasma power, temperature, etc. According to an embodiment, a suitable duration may be between about 1 and 60 minutes. For example, for pretreatment of a copper seed layer, the exposure duration may be between about 10 and 300 seconds.

[0120] In addition, as described in the '770 application, plasma pretreatment can provide an additional benefit, such that metal in portions of the seed layer that have been reduced to their elemental (non-oxidized) state by the pretreatment reflows. This reflow process can reduce pores and gaps in the metal seed layer by moving and redistributing metal atoms, thereby improving seed coverage and / or smoothness, thereby forming a more uniform and continuous metal seed layer. In some embodiments, the metal in the metal seed layer can reflow due to one or more of the following factors that are believed (without being limited to a particular theory) to cause the metal atoms to enter a more excited state and thus become more mobile: exposure to elevated temperature, reduced pressure, exposure to UV radiation from a dedicated UV source, exposure to UV radiation generated by a reducing plasma, and / or exposure to free radicals and / or ions in the plasma. In addition, such reflow can result in a film that integrates the metal that was reduced (i.e., recovered from the metal oxide layer) by the pretreatment into the portion of the metal seed layer that was never oxidized. The film can be substantially continuous and conformal on the contour metal seed layer with the underlying portion of the seed layer that was never oxidized. Thus, the regenerated metal film resists delamination and the like, which is often believed to occur when oxides are eliminated by other techniques.

[0121] Plasma processing device equipped with color sensor

[0122] A plasma treatment apparatus for reducing metal oxides present on the surface of a metal seed layer of a semiconductor substrate prepared for a subsequent electroplating operation is disclosed. The apparatus includes: a processing chamber having at least one processing station in the processing chamber; a substrate holder configured to hold a substrate at the processing station; a plasma generator (configured to generate plasma in the processing chamber and / or provide plasma to the processing chamber); and a controller having non-transitory computer-readable instructions for operating the apparatus. The instructions of the controller may include instructions for operating the plasma generator to generate plasma in the processing chamber. In some embodiments, the instructions generate plasma away from the processing chamber (as further described below) and then provide it to the processing chamber. In any case, execution of the plasma generation (and any related) instructions causes the plasma to contact the surface of the substrate at the processing station to treat the substrate by reducing the metal oxides on the surface. However, in addition to the above features, the plasma treatment apparatus (electroplating pretreatment apparatus) disclosed herein also includes a color sensor, which is used to combine with the controller to provide real-time in-situ estimation (and continuous monitoring in some cases) of the performance of the plasma pretreatment apparatus.

[0123] Thus, the controller may execute instructions for substrate processing operations similar to those described above: operating a plasma generator to generate plasma at a processing station and / or providing plasma to a processing chamber so that the plasma contacts a surface of a substrate at the processing station to process the surface by reducing metal oxides on the surface; operating the color sensor to measure a post-plasma contact color signal from the surface after the plasma contacts the substrate surface, the color signal having one or more color components; estimating the extent of oxide reduction due to plasma processing based on the post-plasma contact color signal. Additional operations that may be performed by the controller include, but are not limited to: providing a semiconductor substrate to a processing station within a processing chamber, operating a remote plasma source in a plasma generation operation, controlling exposure of an oxidized metal seed layer of a substrate to plasma, and the like.

[0124] The color sensor may be positioned / set / installed at various locations within the plasma processing apparatus. For example, in some embodiments, the color sensor may be positioned / set / installed within the plasma processing chamber itself, such that the sensor may be configured to measure a color signal (or signals) from a substrate when the substrate is located at a processing station (in the chamber) for plasma processing. In other embodiments, the color sensor may be positioned / set / installed within an inbound or outbound load lock of the apparatus (which provides a substrate entrance into and out of the plasma processing chamber). In such an arrangement, the color signal (or signals) after plasma contact may be measured in situ by a color sensor located in the outbound load lock, and thus an estimate of the plasma pre-treatment efficiency may be provided, although not in real time during plasma processing. However, in addition, if another color sensor is installed in the inbound load lock, the color signal before plasma contact may be additionally measured before plasma processing, and thus a comparison of the color signal before plasma contact and the color signal after plasma contact provides an estimate of the oxide removal efficiency based on the pre-plasma contact and the post-plasma contact.

[0125] In some embodiments, the hardware components of the color sensor may include a fiber optic sensor head and a sensor body; and the sensor body may include a color signal processing module having computer-readable instructions for processing color signals. Therefore, the above discussion of color sensor positioning / mounting more precisely applies to the fiber optic head of the color sensor. This will be further described below in association with various figures. Before these details, various other aspects of the plasma processing apparatus are first described: One interesting aspect is the showerhead feature of the plasma processing apparatus located between the plasma source and the semiconductor substrate. In some embodiments, it is desired that mainly the free radicals in the plasma contact the substrate and reduce the oxides thereon (as opposed to the ions in the plasma), and the showerhead features described below can be used to filter out the ions of the plasma so that only the free radicals of the plasma reach the surface of the substrate.

[0126] Figure 4 A cross-sectional schematic diagram of an example of a plasma processing apparatus is shown. Plasma processing apparatus 400 includes a processing chamber 450 having a single substrate processing station, such as provided by a substrate holder 405 (which may be a pedestal) for holding a substrate 410. Plasma processing apparatus 400 also includes a plasma generator configured to generate plasma. Here, remote plasma source 440 remotely generates plasma and then provides it to the processing chamber through a showerhead 430 (which is located between substrate 410 and remote plasma source 440). However, in other embodiments, the plasma generator can generate plasma from within the processing chamber itself.

[0127] The reducing gaseous species 420 may flow from the remote plasma source 440 through the showerhead 430 toward the substrate 410. A remote plasma may be generated in the remote plasma source 440 to generate free radicals of the reducing gaseous species 420. The remote plasma may also generate ions and other charged species of the reducing gaseous species. For example, the coil 444 may surround the wall of the remote plasma source 440 and generate the remote plasma within the remote plasma source 440.

[0128] Remote plasma can also generate photons from the reducing gaseous material, such as UV radiation. In some embodiments, the plasma treatment device can further include a UV source. The UV source can include a UV broadband lamp, such as a mercury lamp, a UV excimer lamp, a UV excimer laser, and other suitable UV sources. Aspects of the UV source are described in U.S. Patent Application No. 13 / 787,499 (Agent File No. LAMRP027), filed on March 6, 2013, which is incorporated herein by reference in its entirety and for all purposes. In some embodiments, the reducing gaseous material can be exposed to UV radiation from the UV source to form free radicals and other charged species of the reducing gaseous material, which can react with the metal oxide surface of the metal seed layer to reduce the metal oxide.

[0129] In some embodiments, the coil 444 can be in electrical communication with a radio frequency (RF) power source or a microwave power source. An example of a remote plasma source 440 having an RF power source can be found in . Another example of a radio frequency remote plasma source 440 can be found in , which can operate at 440 kHz and can be used as a subunit bolted onto a larger device to process one or more substrates in parallel. In some embodiments, microwave plasma can be used with a 440 kHz remote plasma source such as that manufactured by MKS Instruments. The microwave plasma may be configured to operate at a frequency of 2.45 GHz.

[0130] In embodiments using a radio frequency power source, the radio frequency generator can be operated at any suitable power to form a plasma of the desired free radical species composition. Examples of suitable powers include, but are not limited to, powers between about 0.5 kW and about 6 kW. Similarly, the radio frequency generator can provide radio frequency power at a suitable frequency, for example, for an inductively coupled plasma, a suitable frequency is 13.56 MHz.

[0131] The reducing gaseous species 420 is delivered from the gas inlet 442 and delivered into the interior volume of the remote plasma source 440. The power supplied to the coil 444 can generate a remote plasma with the reducing gaseous species 420 to form free radicals of the reducing gaseous species 420. The free radicals formed in the remote plasma source 440 can be delivered in the gas phase toward the substrate 410 through the showerhead 430. An example of a remote plasma source 644 having such a configuration is described in U.S. Patent No. 8,084,339 (Attorney Docket No. NOVLP414), issued on December 27, 2011, which is incorporated herein by reference in its entirety for all purposes. The free radicals of the reducing gaseous species 420 can reduce the metal oxide on the surface of the substrate 410.

[0132] In addition to the free radicals of the reducing gas species, the remote plasma may also generate and include ions and other charged species of the reducing gas species 420. In some embodiments, the remote plasma may include neutral molecules of the reducing gas species 420. Some of the neutral molecules may be recombinant molecules from the charged species of the reducing gas species 420. The neutral species or recombinant molecules of the reducing gas species 420 may also reduce metal oxides on the surface of the substrate 410, although they may take longer than the free radicals of the reducing gas species 420 to react and reduce the metal oxides. The ions may drift to the surface of the substrate 410 and reduce the metal oxides, or if the substrate support 405 has an oppositely charged bias, the ions may be accelerated toward the surface of the substrate 410 to reduce the metal oxides. Having species with higher ion energy may allow deeper implantation into the metal seed layer to further generate metastable free radical species from the surface of the substrate 410. For example, if the substrate 410 has high aspect ratio features, such as between about 10:1 and about 60:1, ions with higher ion energies can penetrate deeper into these features to reduce the metal oxide more throughout the feature. In contrast, some radicals of the reducing gas species 420 originating from the remote plasma generation can recombine in the field or near the top of the feature. Ions with higher ion energies (e.g., 10 eV-100 eV) can also be used to re-sputter and reflow the metal in the metal seed layer, which can result in more uniform seed coverage and reduce the aspect ratio of subsequent electroplating or metal deposition (e.g., PVD, CVD, ALD).

[0133] exist Figure 4 In the embodiment of the present invention, the plasma device 400 can actively cool or otherwise control the temperature of the substrate 410. In some embodiments, it may be desirable to control the temperature of the substrate 410 to control the rate of the reduction reaction during processing and the uniformity of exposure to the remote plasma. It may also be desirable to control the temperature of the substrate 410 to reduce the effects of oxidation on the substrate 410 before, during, and / or after processing.

[0134] In some embodiments, the plasma device 400 may include a movable member 415, such as a lift pin, capable of moving the substrate 410 away from or toward the substrate support 405. The movable member 415 may contact the lower surface of the substrate 410 or pick up the substrate 410 from the substrate support 405. In some embodiments, the movable member 415 may vertically move the substrate 410 and control the spacing between the substrate 410 and the substrate support 405. In some embodiments, the movable member 415 may include two or more actuatable lift pins. The movable member 415 may be configured to extend away from the substrate support 405 between about 0 inches and about 5 inches or more. The movable member 415 may extend the substrate 410 away from the hot substrate support 405 and toward the cold spray 430 to cool the substrate 410. The movable member 415 may also retract to move the substrate 410 toward the hot substrate support 405 and away from the cold spray 430, thereby heating the substrate 410. The temperature of the substrate 410 may be adjusted by positioning the substrate 410 via the movable member 415. When the substrate 410 is positioned, the showerhead 430 and the substrate support 405 may be maintained at a constant temperature.

[0135] In some embodiments, the plasma processing apparatus 400 may include a showerhead 430 that enables the temperature of the showerhead to be controlled. Examples of showerhead configurations that enable temperature control are described in U.S. Patent No. 8,137,467 (Attorney Docket No. NOVLP246), issued on March 20, 2012, and U.S. Patent Publication No. 2009 / 0095220 (Attorney Docket No. NOVLP246X1), published on April 16, 2009, both of which are incorporated herein by reference in their entirety for all purposes. Another example of a showerhead configuration that enables temperature control is described in U.S. Patent Publication No. 2011 / 0146571 (Attorney Docket No. NOVLP329), published on June 23, 2011, which is incorporated herein by reference in its entirety for all purposes. In order to actively cool the showerhead 430, a heat exchange fluid can be used, for example, deionized water or a heat transfer liquid manufactured by Dow Chemical Company of Midland, Michigan. In some embodiments, the heat transfer fluid can flow through a fluid channel (not shown) in the showerhead 430. In addition, the showerhead 430 can use a heat exchange system (not shown), such as a fluid heater / refrigerator to control the temperature. In some embodiments, the temperature of the showerhead 430 can be controlled to be less than about 30°C, for example, between about 5°C and about 20°C. The showerhead 430 can be cooled to reduce damage to the metal seed layer that may be caused by overheating during the processing of the substrate 410. For example, before and after processing the substrate 410, the showerhead 430 can also be cooled to a temperature lower than the substrate 410.

[0136] In some embodiments, the showerhead 430 may include a plurality of holes. Increasing the size of the holes in the showerhead 430 and increasing the number of holes and / or reducing the thickness of the showerhead 430 may allow a larger flow of free radicals, ions, and UV radiation from the reducing gaseous material 420 to pass through the showerhead 430. Exposing the metal seed layer to more free radicals, ions, and UV radiation may provide more UV exposure and energy substances to reduce the metal oxide in the metal seed layer. In some embodiments, the showerhead 430 may include between about 100 and about 900 holes. In some embodiments, the average diameter of the holes may be between about 0.05 and about 0.5 inches. This may result in an open area of ​​between about 3.7% and about 25% in the showerhead 430 due to the holes. In some embodiments, the showerhead 430 may have a thickness between about 0.25 and about 3.0 inches.

[0137] In some embodiments, the substrate support 405 can be configured to move to and from the showerhead 430. The substrate support 405 can extend vertically to control the spacing between the substrate 410 and the showerhead 430. When reducing the metal oxide on the substrate 410, the uniformity and rate of reduction on the substrate 410 can be adjusted. For example, if the substrate support 405 is closer to the showerhead 430, the reduction of the metal oxide on the surface of the substrate 410 can be carried out faster. However, the center of the substrate 410 may become hotter than the edge of the substrate 410, which can result in a less uniform reduction process. Therefore, the spacing between the substrate 410 and the showerhead 430 can be adjusted to obtain the desired rate and uniformity for processing the substrate 410. In some embodiments, the substrate support 405 can be configured to extend between about 0 inches and about 5 inches or more than about 5 inches from the showerhead 430.

[0138] In some embodiments, the temperature of the substrate support 405 can also be adjusted. In some embodiments, the substrate support 405 can be a base having one or more fluid channels (not shown). Depending on the temperature of the heat transfer fluid, the fluid channels can circulate the heat transfer fluid within the base to actively cool or actively heat the base. Embodiments including such fluid channels and heat transfer fluids can be described as active cooling base systems previously discussed herein. Circulating the heat transfer fluid through one or more fluid channels can control the temperature of the substrate support 405. The temperature control of the substrate support 405 can control the temperature of the substrate 410 to a more precise degree. In some embodiments, the temperature of the substrate support 405 can be adjusted to between about 0°C and about 400°C.

[0139] In some embodiments, the plasma processing apparatus 400 may include one or more gas inlets 422 to flow a cooling gas 460 through the processing chamber 450. The one or more gas inlets 422 may be located above, below, and / or to the side of the substrate 410. Some of the one or more gas inlets 422 may be configured to flow the cooling gas 460 in a direction substantially perpendicular to the surface of the substrate 410. In some embodiments, at least one of the gas inlets 422 may deliver the cooling gas 460 through the showerhead 430 to the substrate 410. Some of the one or more gas inlets 422 may be parallel to the plane of the substrate 410 and may be configured to deliver a lateral flow of the cooling gas 460 flowing across the surface of the substrate 410. In some embodiments, the one or more gas inlets 422 may deliver the cooling gas 460 above and below the substrate 410. The flow of the cooling gas 460 flowing through the substrate 410 may enable the substrate 410 to be cooled rapidly. The rapid cooling of the substrate 410 may reduce oxidation of the metal seed layer in the substrate 410. Such cooling of the substrate 410 may be performed before and after processing of the substrate 410. The flow rate of the cooling gas 460 used for cooling may be between about 0.1 standard liters per minute (slm) and about 100 slm.

[0140] Examples of cooling gas 460 may include relatively inert gases such as nitrogen, helium, neon, krypton, xenon, radon, and argon. In some embodiments, cooling gas 460 may include at least one of nitrogen, helium, and argon.

[0141] In some embodiments, the cooling gas 460 may be delivered at room temperature, such as between about 10° C. and about 30° C. In some embodiments, the cooling gas 460 may be delivered at a temperature below room temperature. For example, the cold inert gas may be formed by expanding a cold liquid (e.g., liquid argon, helium, or nitrogen) into a gas. Thus, the temperature range of the cooling gas 460 used for cooling may be extended to any range between about -270° C. and about 30° C.

[0142] In some embodiments, the plasma treatment apparatus 400 can be part of or integrated with an electroplating apparatus (not shown). During exposure to the ambient conditions, oxidation of the metal seed layer in the substrate 410 can occur rapidly. By attaching or otherwise connecting the plasma treatment apparatus 400 to the electroplating apparatus, the duration of exposure to the ambient conditions of the substrate 410 can be reduced. For example, the transfer time between the plasma treatment apparatus and the electroplating apparatus after treatment can be between about 15 seconds and about 90 seconds, or less than about 15 seconds.

[0143] Table I summarizes exemplary ranges of process parameters that may be used with certain embodiments of the plasma processing apparatus 400.

[0144] Table I

[0145]

[0146]

[0147] The controller 435 may contain instructions for controlling parameters for the operation of the plasma processing apparatus 400. The controller 435 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc. The plasma processing apparatus may be configured to perform a plurality of operations that are not limited to processing a substrate with a remote plasma. The plasma processing apparatus may be configured to effectively transfer (e.g., load / unload) a substrate to and from an electroplating apparatus, an electroless plating apparatus, or other metal deposition apparatus. The plasma processing apparatus may be configured to effectively control the temperature of the substrate by positioning the substrate using a movable member and / or using a substrate support. The plasma processing apparatus may be configured to effectively control the temperature of the substrate by controlling the temperature of the substrate support and the temperature of the showerhead. The plasma processing apparatus may be configured to adjust the rate of the reduction reaction and the uniformity of the reduction reaction by positioning the substrate support relative to the showerhead. The plasma processing apparatus may be configured to control the environmental conditions around the substrate by controlling the gas and gas flow rate delivered to the processing chamber. Such operations may improve the processing of the substrate while also integrating additional operations into a single stand-alone apparatus. Thus, a single device can be used to process and cool the substrate rather than using two separate modules. In addition, by configuring the plasma processing apparatus to be able to perform some of the above operations, the plasma processing apparatus can reduce possible oxidation of the metal seed layer before, during and after substrate processing.

[0148] Figure 4 A plasma processing apparatus with a single processing station is shown. However, the plasma processing apparatus may have multiple processing stations so that multiple substrates may be processed in parallel. According to an embodiment, one or more of the processing stations may have a color sensor positioned / mounted to measure the color signal and thus assess the oxide removal performance in situ and in real time during the oxide removal process. Figure 5ASuch a multi-station plasma processing apparatus 500 is schematically illustrated with four processing stations 541-544. In this embodiment, a single processing chamber 510 defines a high vacuum environment for all four stations, however, in some cases, a gas curtain may flow between different processing stations to isolate them volumetrically from each other (at least to some extent). In addition, this embodiment employs a rotating conveyor 520 on which a substrate is positioned, which can be used to rotate the substrate between the four processing stations. Thus, depending on the embodiment, the four processing stations may perform the same or different processing operations. In addition, even if the same processing operation (or operations) is performed at each of the four stations, it may still be advantageous to rotate the semiconductor substrate through all four processing stations so that any systematic differences in processing are "averaged out" over the four stations.

[0149] The substrate enters the processing device 500 through the inbound load lock 531 and leaves through the outbound load lock 532. Through the operation of the load lock, the semiconductor substrate can be entered into and removed from the device without destroying the high-pressure vacuum environment provided by the process chamber 520. Specifically, in the embodiment shown in the figure, this can be achieved by closing the load lock seals 533 and 534 (which lead to the process chamber) after placing the substrate in the load locks 531 and 532, and then opening the load lock doors 535 and 536 (which lead to the surrounding environment outside the device).

[0150] Within the apparatus 500, substrates are transferred to and from the inbound and outbound load locks 531 and 532 via the wafer transport apparatus robot 540. Note that in this embodiment, the robot 540 only transfers wafers to the processing stations closest to it, namely, processing stations 541 and 542. The other two processing stations 543 and 544 are accessed by the rotation of the carousel 520. Additional seals 561 and 562 may allow the wafer transport apparatus robot 540 to enter the processing chamber 510.

[0151] The color sensor may be positioned / installed / disposed at various locations within the plasma processing apparatus 500. Figure 5A As shown, color sensor 595 is shown located at processing station 541. The rotation of substrates between processing stations via a rotating conveyor may make it feasible to have only a single color sensor in a processing chamber. Figure 5A Also shown is apparatus 500 having color sensors 591 and 592 located in the inbound and outbound load locks, respectively. As described above, this provides the ability to measure color signals before and after a plasma pre-treatment process.

[0152] Figure 5B(i) to 5B(iii) provide a more detailed view of the installation of the color sensor in the load lock. In particular, Figure 5B (i) shows a load lock 530 with a color sensor 596, which may correspond to Figure 5A Outbound load lock 532 in. Figure 5B (ii) shows that Figure 5B The vertical cross section shown by the dashed line 505 in (i) (with Figure 5A and 5B (i) Relative, Figure 5A and 5B (i) shows the load lock viewed from above). Figure 5B (ii) The vertical cross-section shown illustrates the positioning of the color sensor, and more specifically illustrates that the hardware components of this particular color sensor include a fiber optic sensor head 596A coupled to one or more fiber optic strands bundled together in a single cable housing 596B, which terminates in what may be referred to as a color sensor body 596C (as described above) that holds the actual color detection electronics. In some embodiments, the sensor body 596C may also include a color signal processing module having logic and / or computer readable instructions for processing color signals (sent from the fiber optic sensor head) beyond basic detection (e.g., calibration, contrast enhancement, etc.), and therefore, it should be noted that the above discussion of color sensor positioning / mounting applies more precisely to the fiber optic head of the color sensor, rather than the entire color sensor. Such as integrated into a plasma processing apparatus Figure 2 An example of such a color sensor that measures the three color components a*, b*, and L* is shown as a Micro-Epsilon model color sensor manufactured by Micro-Epsilon of Germany.

[0153] Figure 5B (ii) shows the color sensor 596, or more precisely the fiber tip 596A of the color sensor, pointing toward the edge of the wafer 507 within the load lock 530. Note that since the color sensor is trained on areas of the wafer other than the center of the wafer, in principle, rotation of the wafer can enable multiple color signals to be measured at multiple azimuthally rotated points on the wafer surface. This may be more feasible when the sensor is mounted in the process chamber rather than in the load lock, depending on where the rotatable substrate holder may be located. Multiple azimuthally distributed color signal measurements are of course not required, but they can provide enhanced accuracy and precision by verifying oxide removal performance around the entire wafer perimeter.

[0154] Figure 5B (iii) shows another vertical cross section, this time zoomed in on Figure 5B(ii) The area indicated by the dashed oval 506. Here, the fiber optic color sensor head 596A is shown in detail positioned within a mount 598 located within the upper wall of the load lock 530. The translucent quartz window 597 allows for the viewing of the substrate 507 ( Figure 5B (ii)) The reflected light reaches the color sensor 596 within its mounting 598.

[0155] In some embodiments, the color sensor may additionally include a light source for illuminating the substrate surface. This may also be via optical fiber; in other words, one or more fiber optic lines bundled together in cable 596B may transmit light generated from sensor body 596C to sensor head 596A, where the light is emitted and directed toward the substrate. Typically, a substantially white light is used and trained on a relatively small spot on the substrate surface. In the case where the sensor head is positioned at 90 degrees relative to the substrate surface and is positioned immediately adjacent thereto (e.g., Figure 5B (ii)), the reflected light is collected by sensor head 596A and brought back to the actual electronic color detector located in the color sensor body 596C via cable 596B. Of course, the physical configuration of the color sensor includes multiple physical units including the body, cable housing and fiber optic sensor head, such as Figure 5B Whether the color sensor is schematically depicted in (ii), or is configured as a single physical unit, is not critical to the operation and functionality of the inventive concepts disclosed herein.

[0156] In some embodiments, one or more color sensors of a plasma processing device are configured to send (electronically) signals to a controller of the device (e.g., controller 550 in FIG. 5 ). The controller can be configured to receive the signals and process them to implement any of the color signal analysis methods described herein for estimating the extent of oxide reduction after (or during) plasma treatment. However, in some embodiments, the color signal processing module within the color sensor itself can have sufficient processing power to implement the methods disclosed herein to assess the extent of oxide reduction. In these types of embodiments, the color sensor can include logic for signaling the main device controller when there is a detected problem with the plasma treatment process.

[0157] Fig. 6A An exemplary flow chart illustrating a method of processing a substrate having a metal seed layer is shown. Figures 7A-7D An example of a cross-sectional schematic diagram illustrating various stages of processing a substrate having a metal seed layer using a plasma processing apparatus is shown. Figures 7A-7D The corresponding cross-sectional diagram in Fig. 6A Some of the steps discussed in .

[0158] exist Fig. 6A In step 605a, processing 600a may start from step 605a, wherein a substrate is provided into a processing chamber. The substrate may include a metal seed layer, wherein a portion of the metal seed layer has been converted into an oxide of the metal. Before the substrate is processed by remote plasma, the substrate may be loaded into a processing chamber of a plasma processing device. In some embodiments, the substrate may be disposed on one or more movable members in an actuated position. In some embodiments, an inert gas may flow through the processing chamber to cool the substrate during loading. This may reduce additional oxidation of the substrate during loading. In some embodiments, when the substrate is loaded into the processing chamber, the processing chamber may be closed and evacuated to a vacuum or low pressure. This may provide a substantially oxygen-free environment. The pressure of the processing chamber may be between about 0.5 Torr and about 6 Torr, for example, between about 0.5 Torr and 3 Torr. Low pressure may reduce the presence of oxygen in the environment. Therefore, loading the substrate into the processing chamber under such conditions may reduce additional oxidation of the metal seed layer.

[0159] Fig. 7A An example of a cross-sectional schematic diagram of a plasma processing apparatus 700 is shown at a stage (e.g., at step 605a) of processing a substrate having a metal seed layer. The plasma processing apparatus 700 includes a substrate support 705 in a processing chamber 750, a remote plasma source 740 on the substrate support 705, and a showerhead 730 between the remote plasma source 740 and the substrate support 705. A movable member 715 may extend from the substrate support 705 toward the showerhead 730 to position the substrate 710. Examples of movable members may include lift pins and peripheral clamps. The substrate 710 may include a metal seed layer, wherein the metal seed layer includes at least one of Cu, Co, Ru, Pd, Rh, Ir, Os, Ni, Au, Ag, Al, and W. In some embodiments, the thickness of the metal seed layer may be less than about

[0160] exist Fig. 7A In the embodiment of the present invention, the movable member 715 in the processing chamber 750 can position the substrate 710 in the actuated position. The actuated position can place the substrate 710 in a position that is smaller than the unactuated position (e.g., Figure 7B The distance A1 between the substrate 710 and the showerhead 730 can be between about 0.05 inches and about 0.75 inches in the actuated position. The distance B1 between the substrate 710 and the substrate support 705 can be any desired distance. For example, the distance B1 can be greater than about 1 inch, such as between about 1 inch and about 5 inches. The showerhead 730 can be maintained at a relatively cool temperature, such as less than about 30° C.

[0161] Back to Fig. 6A, in step 610a, the substrate is moved toward a substrate support in the processing chamber. In some embodiments, the substrate can be moved to an unactuated position via a movable member. The unactuated position is farther from the showerhead in the processing chamber than the actuated position. In some embodiments, the substrate in the unactuated position can be in contact with the substrate support. For example, the movable member can be retracted so that the substrate can rest on the substrate support. In some embodiments, there can be a gap between the substrate support and the substrate, and heat transfer can occur via conduction, convection, radiation, or a combination thereof. The substrate support can be heated, which in turn can heat the substrate. The substrate support can be heated to a processing temperature, such as a temperature between about 0°C and about 400°C. The temperature of the substrate support can depend on the metal seed layer of the substrate. For example, for cobalt, the substrate support can be heated between about 250°C and about 300°C, and for copper, the substrate support can be heated between about 75°C and about 100°C. The higher temperature of the substrate can accelerate the metal oxide reduction reaction. However, the temperature can be selected not to exceed the agglomeration temperature of the metal seed layer. While the substrate is heated, the substrate may be exposed to a remote plasma process.

[0162] Figure 7B An example of a cross-sectional schematic diagram of a plasma processing apparatus 700 at a stage of processing a substrate having a metal seed layer (e.g., at step 610a) is shown. The plasma processing apparatus 700 includes a substrate 710 above a substrate support 705, wherein the substrate 710 is in an unactuated position. In the unactuated position, the substrate 710 is positioned at a distance A2 from the showerhead 730 and is farther away from the showerhead 730 than in the actuated position. The distance A2 between the showerhead 730 and the substrate 710 may be greater than about 1 inch, such as between about 1 inch and about 5 inches. The substrate 710 and the substrate support 705 may contact each other, or the distance B2 between the substrate 710 and the substrate support 705 may be relatively small to allow effective heat transfer between the substrate 710 and the substrate support 705. In some embodiments, the distance B2 may be between about 0 inches and about 0.5 inches. In some embodiments, the movable member 715 may be retracted so that the substrate 710 rests on the substrate support 705. The substrate support 705 may position the substrate 710 relative to the showerhead 730 by vertically moving the substrate support 710. The showerhead 730 may be maintained at a relatively cool temperature, such as less than about 30°C.

[0163] The distance A2 can be adjusted during substrate processing and the reaction rate and reaction uniformity can be adjusted. For example, if the substrate support 705 is closer to the showerhead 730, the rate of reduction can be performed faster, but a less uniform result is achieved. The distance A2 can be adjusted by vertical movement of the substrate support 705. In some embodiments, the substrate support 705 can be moved from a first position to a second position in the processing chamber, wherein the distance between the first position and the second position is greater than about 1 inch. The increased freedom for positioning the substrate support 705 provides greater flexibility in adjusting the rate and uniformity of the subsequent reduction process.

[0164] Back to Fig. 6A In step 615a, a remote plasma may be formed from a reducing gas species in a remote plasma source, wherein the remote plasma includes free radicals of the reducing gas species. The remote plasma may be formed by exposing the reducing gas species to an energy source. The energy source may generate free radicals, ions, and other charged species that may flow toward the substrate. In some embodiments, the energy source may be an RF discharge. When the remote plasma is formed, the substrate may be heated to or has been heated to a desired processing temperature. In some embodiments, a showerhead is connected to the remote plasma source and filters out ions so that free radicals of the reducing gas species may flow toward the substrate in the processing chamber.

[0165] In step 620a, the metal seed layer of the substrate is exposed to free radicals of a reducing gaseous substance. A portion of the metal seed layer may include an oxide of the metal seed layer. Ions, free radicals, and other charged species formed in the remote plasma flow flow through the shower head, and the ions and other charged species may be filtered out so that the substrate is substantially exposed to free radicals of the reducing gaseous substance. The metal oxide may react with the free radicals of the reducing gaseous substance or the reducing gaseous substance itself to convert the metal oxide into a metal. The reaction is carried out under conditions that convert the metal oxide into a metal. The metal oxide in the metal seed layer is reduced to form a film integrated with the metal seed layer. Using a reducing gaseous substance to reduce the metal oxide in the metal seed layer is described in U.S. Application No. 13 / 787,499 (Agent File No. LAMRP027) filed on March 6, 2013, which is incorporated herein by reference in its entirety and for all purposes. In some embodiments, when the shower head is maintained at a temperature below about 30°C, the free radicals of the reducing gaseous substance flow through the shower head.

[0166] Figure 7CAn example of a cross-sectional schematic diagram of a plasma processing apparatus 700 at a stage of processing a substrate having a metal seed layer (e.g., at steps 615a and 620a) is shown. The plasma processing apparatus 700 includes a remote plasma source 740 on a substrate 710 and one or more coils 744 surrounding the wall of the remote plasma source 740. A gas inlet 742 may be connected to the remote plasma source 740 to deliver a reducing gas substance 720 into the internal volume of the remote plasma source 740. The reducing gas substance 720 may flow at a flow rate between about 500 sccm and about 30,000 sccm, which may be applicable to any substrate size. In some embodiments, the reducing gas substance 720 may include at least one of H2, NH3, CO, B2H6, sulfite compounds, carbon and / or hydrocarbons, phosphites, and N2H4. The power supplied to the one or more coils 744 may generate a remote plasma of the reducing gas substance 720 in the remote plasma source 740. The RF plasma power supplied to the coils 744 may be between about 0.5 kW and about 6 kW. The remote plasma may include radicals of the reducing gas species 720, such as H * NH * NH2 * or N2H3 * The remote plasma may also include ions and other charged species, but the showerhead 730 may filter them out so that the radicals of the reducing gas species 720 reach the substrate 710. The radicals of the reducing gas species 720 flow from the remote plasma source 740 through the showerhead 730 and reach the surface of the substrate 710 in the processing chamber 750. The showerhead 730 may be maintained at a relatively cool temperature, such as less than about 30° C. The cooled showerhead 730 may limit excess heat from reaching the substrate 710 and avoid damaging the metal seed layer in the substrate 710.

[0167] exist Figure 7C , the substrate 710 can remain in the unactuated position. The distance A3 between the substrate 710 and the showerhead 730 can be adjusted by moving the substrate support 705. Adjusting the distance A3 can adjust the rate of the reduction reaction occurring at the substrate 710 and the uniformity of the reduction reaction. For example, a shorter distance A3 can result in a faster conversion of the metal oxide, but a lower uniformity, while a longer distance A3 can result in a slower conversion of the metal oxide, but a greater uniformity. In some embodiments, the distance A3 can be the same as the distance A2. The movable member 715 can be retracted so that the substrate 710 and the substrate support 705 remain in contact, or the distance B3 between the substrate 710 and the substrate support 705 can be adjusted. Figure 7B The distance B2 in is the same.

[0168] The temperature of the substrate support 705 can be adjusted via an active heating or active cooling system. The temperature can be adjusted depending on the metal seed layer in the substrate 710 being processed. For example, when switching between two different metal seed layers that need to operate at two different temperature regimes, the temperature of the substrate support 705 can be changed. For example, for a cobalt seed layer, the substrate support 705 can be heated between about 250°C and about 300°C, while for a copper seed layer, it can be switched to heating between about 75°C and about 100°C.

[0169] Back to Fig. 6A , in step 625a, the substrate is exposed to a cooling gas. The cooling gas may include at least one of argon, helium, and nitrogen. In some embodiments, the cooling gas may be produced by expanding a cooling liquid into a gas. Exposing the substrate to the cooling gas may cool the substrate to a temperature below about 30°C. Therefore, the cooling gas may be delivered at a temperature below ambient conditions to cool the substrate. In some embodiments, before exposing the substrate to the cooling gas, the substrate may be moved to an actuated position via a movable member. The substrate may be exposed to the cooling gas while in the actuated position for faster cooling. In some embodiments, the substrate may be transferred to an electroplating device after exposing the substrate to the cooling gas. Alternatively, the substrate may be transferred to an electroless plating device or other metal deposition device. In some embodiments, after exposing the substrate to the cooling gas, the processing chamber may be exhausted to atmospheric conditions with an exhaust gas.

[0170] Fig.7D An example of a cross-sectional schematic diagram of a plasma processing apparatus 700 at a stage of processing a substrate having a metal seed layer (e.g., at step 625a) is shown. The plasma processing apparatus 700 may include one or more cooling gas inlets 722 for delivering cooling gas 760. The cooling gas inlet 722 may be positioned around the substrate 710, including above and to the side of the substrate 710. The cooling gas 760 may be directed onto the substrate 710 through the showerhead 730 and perpendicular to the substrate plane. The cooling gas 760 may also be directed onto the substrate 710 and parallel to the substrate plane from the cooling gas inlet 722 on the side of the processing chamber 750. The cooling gas 760 may flow into the processing chamber 750 at a flow rate between about 0.1 slm and about 100 slm. The cooling gas inlet 722 may flush the cooling gas 760 through the substrate 710 to quickly cool the substrate 710 before transferring the substrate to an electroplating apparatus, an electroless plating apparatus, or other metal deposition apparatus. In some embodiments, the substrate 710 may be cooled without closing or cooling the substrate support 705. This may enable the substrate 710 to be processed and cooled within a single processing chamber 750 rather than using a dual chamber design with separate heating and cooling zones.

[0171] exist Fig.7D In the embodiment, the substrate 710 can be in the actuated position. The distance A4 between the showerhead 730 and the substrate 710 can be between about 0.05 inches and about 0.75 inches. In some embodiments, the distance A4 can be about Fig. 7A By positioning the substrate 710 closer to the cooled showerhead 730 and away from the heated substrate support 705, the substrate 710 can be cooled at a faster rate. The movable member 715 can lift the substrate 710 away from the substrate support 705 and toward the showerhead 730. The distance B4 between the substrate support 705 and the substrate 710 can be greater than about 1 inch, or between about 1 inch and about 5 inches. In some embodiments, the distance B4 can be about 1 inch to about 5 inches. Fig. 7A In some embodiments, when the substrate 710 is in the actuated position and cooled to approximately room temperature, the process chamber 750 can be vented to atmospheric conditions and transferred to an electroplating apparatus, an electroless plating apparatus, or other metal deposition apparatus.

[0172] Figure 6B An exemplary flow chart illustrating another method of processing a substrate having a metal seed layer is shown. At step 605b of method 600b, a substrate having a metal seed layer may be provided in a processing chamber, as generally described at step 605a of method 600a. The metal seed layer may have a portion that has been converted to an oxide of the metal.

[0173] In step 610b, a remote plasma of a reducing gaseous substance may be formed in a remote plasma source, wherein the remote plasma includes one or more of free radicals, ions, and UV radiation from the reducing gaseous substance. The energy of the remote plasma may be increased to produce higher energy substances, including higher energy ions. The higher energy ions may be produced in a high density plasma (HDP) processing system and / or a sputtering system. The remote plasma may also produce UV radiation due to the excitation of the reducing gaseous substance. The UV radiation produced may have a wavelength between about 100nm and about 400nm. For example, the UV radiation produced may include short wavelength UV light, such as a wavelength between about 120nm and about 200nm, and long wavelength UV light, such as a wavelength between about 200nm and about 400nm. In addition, the remote plasma may include neutrals and / or recombinant molecules that produce reducing gaseous substances.

[0174] In step 615b, the metal seed layer of the substrate is exposed to plasma, wherein the exposure reduces the oxide of the metal and reflows the metal in the metal seed layer. In some embodiments, the reflow of the metal and the reduction of the metal oxide may occur simultaneously. In some embodiments, the remote plasma may include free radicals, ions and UV radiation from the reducing gas species, or some combination thereof. The showerhead between the remote plasma source and the processing chamber may have a thickness, number of holes and average diameter of holes configured to allow free radicals, ions and UV radiation to flow through the showerhead toward the substrate or otherwise pass through the showerhead toward the substrate. Free radicals, ions and UV radiation may enter the processing chamber and reduce the metal oxide in the metal seed layer. High-energy ions may further penetrate from the surface of the substrate to provide a reduction chemistry throughout more metal seed layers. UV radiation may activate the metal oxide surface to improve the thermodynamics of the reduction process, or directly reduce the metal oxide itself. UV radiation may also be absorbed by the reducing gas species and produce free radicals that may reduce the metal oxide. In addition, the neutral molecules of the reducing gas species may further react and reduce the metal oxide in the metal seed layer.

[0175] In some embodiments, the metal in the metal seed layer can be excited and moved when exposed. The metal can be reflowed to reduce gaps and pores in the metal seed layer, thereby reducing the surface roughness of the metal seed layer. The extent of metal reflow can depend on, for example, the temperature of the substrate, the chamber pressure, the reducing gas species, and the intensity of the UV radiation. Since the metal is reflowed and redistributed on the underlying layer, a more uniform and continuous metal seed layer can be formed.

[0176] Example

[0177] The following embodiments illustrate the feasibility of using a color sensor to monitor oxide layer thickness and measure the efficiency of a plasma pretreatment for reducing oxides on a metal seed layer. In particular, the sensitivity of the b* color component to oxide layer thickness will be demonstrated.

[0178] Figure 8Results of experiments performed on 6 wafers with a 200 angstrom oxide layer are shown. For each wafer labeled "W1" to "W6", the value of the b* color component was measured before and after treatment with H2 plasma: the b* measurements labeled "Pre-QSM" on the left were obtained before the H2 plasma treatment, and the b* measurements labeled "Post" on the right were performed after the H2 plasma treatment of the indicated duration (11 seconds, 20 seconds, etc.). It can be seen that for all 6 wafers, the plasma treatment resulted in a significant increase in the value of the b* color component, which was greatest for plasma treatment durations of 60 seconds or longer. Note that for the first wafer labeled "W1", additional b* values ​​were also measured after "treatment" without reducing H2 gas in the processing chamber. This appears to provide the same b* values ​​as the b* values ​​without pretreatment, further confirming that oxide reduction results in a changed value of the b* color component. The results are summarized in the following table:

[0179] Table II

[0180] Processing conditions b* changes <![CDATA[Without H2, 2 kW, 60 s treatment]]> 0.24％ <![CDATA[With H2, 2kW, 11s processing]]> -39.8％ <![CDATA[With H2, 2kW, 20s processing]]> -35.5％ <![CDATA[With H2, 2kW, 40s processing]]> -136.2％ <![CDATA[With H2, 2kW, 60s processing]]> -158.3％ <![CDATA[With H2, 2kW, 120s processing]]> -171.3％ <![CDATA[With H2, 2kW, 300s processing]]> -163.9％

[0181] Figures 9A to 9C The effects of H2 plasma treatment on L*, a* and b* (respectively Figures 9A-9C ) values ​​of each of the three color components. In these experiments, five samples with different oxide layer thicknesses ( and ) wafers were pre-treated. Comparing the three figures, it can be seen that for all oxide layer thicknesses, only the b* color component shows a statistically significant change before and after plasma treatment. Note that for The difference appears to be slightly more significant for thinner oxide layers.

[0182] However, Figure 8 and Figures 9A-9C shows the sensitivity of the b* color component in a benchtop setup, Fig.10 (a), 10(b), 11A and 11B show the efficiency of real-time monitoring of the b* color component in a load lock of a plasma processing device such as in Figure 5A-5B These Figures (10-11B) show the value of the b* color component as a function of time during a "multi-layer recipe" where the wafer passes through the outbound load lock twice.

[0183] First reference Fig.10(a), it can be seen that the first pass of the wafer under the color sensor of the exit load lock occurs at about 370 seconds in the figure and corresponds to the wafer leaving the plasma processing chamber without the plasma already turned on, in other words, it represents the measurement of the b* color component before plasma processing. This first peak has two shoulders surrounding its center where it has its maximum. The reason for this is that the pedestal in the load lock is raised and lowered while holding the wafer, so the higher value in the center of the peak corresponds to the pedestal being in the "up" position and the substrate being closer to the color sensor. This emphasizes the importance of keeping the color sensor at an optimal distance from the wafer surface to maximize the signal-to-noise ratio of the b* component.

[0184] The wafer passes through the color sensor of the outbound load lock for the second time. Fig.10 The peak at about 610 seconds in (a) occurs and corresponds to a wafer leaving the plasma processing chamber after turning on the plasma for oxide reduction. The plasma process had a duration of 60 seconds at a temperature of 250°C (the wafer had a 100 angstrom oxide layer before the plasma treatment). A shoulder is present within the peak at 610 seconds, as seen in the previous peak at 370 seconds, but the overall magnitude of the b* value is significantly reduced, confirming that the b* color component can be used as an indicator of plasma treatment. Fig.10 (b) Zooms in on these two regions (shown as dashed lines) and again highlights the difference in b* color component values ​​before and after plasma treatment.

[0185] again, Fig.10 The shoulder on the peak shown in (a) illustrates the importance of choosing the correct gap between the surface of the substrate and the head of the color sensor in order to have a sufficiently strong b* signal and a sufficient signal-to-noise ratio. Based on experiments such as the one just described, a gap between about 0.1 inches and 5 inches has been found to be sufficient, more preferably, between about 0.4 inches and 1 inch.

[0186] Finally, with Fig.10 (b) Similar data are shown in Fig.11A and Fig. 11B The difference is that in Fig.11A and Fig. 11B In FIG. 5 , the graphs show the results for six wafers (each having a 200 angstrom oxide layer) that have been plasma treated for different durations. Fig.11A The results of 6 plasma treatments (of different durations) at 250°C are shown, Fig. 11B Results for five plasma treatments at 75° C. are shown. For almost all cases, a significant change in the b* color component is shown relative to the component measured from each wafer prior to plasma treatment (labeled “before” in the figure). Fig.11AThe higher temperature (250°C) results in a "max out" (oxide removal saturation) at even only 11 seconds of plasma treatment (for the most part), while Fig. 11B At the lower temperature shown in Figure 1 (75°C), the b* color component changes only slightly at 11 seconds, with significant changes first appearing in the 30 second results and then becoming more apparent at longer durations of up to 300 seconds in the results shown in the figure. Fig.11A and 11B The results shown in show that even at a relatively low temperature of 75° C., only 30 seconds of plasma treatment produced a significant change in the measured b* color component, thereby allowing an assessment of the efficiency of the plasma treatment to be made.

[0187] System Controller

[0188] Plasma processing methods and techniques for evaluating oxide reduction efficiency may be implemented in program instructions that may reside on a system controller for a plasma processing apparatus and / or may reside on a remote non-transitory medium that is accessible from or read by a controller for the plasma processing apparatus. Examples of such system controllers are described in Figure 5A As shown schematically in Figure 5A As shown, the system controller 550 includes one or more memory devices 556, one or more mass storage devices 554, and one or more processors 552. The processor 552 may include one or more CPUs, ASICs, general purpose computers and / or special purpose computers, one or more analog and / or digital input / output connections, one or more stepper motor controller boards, etc.

[0189] In some embodiments, the system controller ( Figure 5A 550) controls the processing tool (e.g. Figure 5ASome or all of the operations of a plasma processing apparatus 500 in the embodiment of the present invention, including the operations of its individual processing stations. Machine-readable system control instructions 558 may be provided to implement / execute the plasma processing method and color sensor operation and color signal analysis described in the present invention. The instructions may be set on a machine-readable, non-transitory medium that can be coupled to and / or read by the system controller. The instructions may be executed on the processor 552, and in some embodiments, the system control instructions are loaded from the mass storage device 554 to the memory device 556. The system control instructions may include instructions for controlling the following parameters: timing, mixture of gas and liquid reactants, chamber and / or station pressure, chamber and / or station temperature, wafer temperature, target power level, RF power level (e.g., DC power level, RF bias power level), RF exposure time, substrate base, chuck and / or sensor position, and other parameters of a specific process performed by the processing tool.

[0190] Semiconductor substrate processing operations may employ various types of processes including, but not limited to, processes associated with etching of films on a substrate, deposition processes such as atomic layer deposition (ALD), which is performed by plasma activation of surface adsorbed film precursors, and other types of substrate processing operations such as plasma-based oxide removal from a metal seed layer in preparation for electroplating, and control of electroplating operations.

[0191] The system control instructions 558 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of the process tool components required to perform the processes of the various process tools. The system control instructions may be encoded in any suitable computer-readable programming language. In some embodiments, the system control instructions are implemented in software, in other embodiments, the instructions may be implemented in hardware, for example, as logic hard-coded in an ASIC (application specific integrated circuit), or, in other embodiments, as a combination of software and hardware.

[0192] In some embodiments, the system control software 558 may include input / output control (IOC) sequencing instructions for controlling the various parameters described above. For example, each stage of one or more deposition and / or etching processes may include one or more instructions for execution by the system controller. Instructions for setting process conditions for a film deposition process stage and / or an etching process stage may be included, for example, in a corresponding deposition recipe stage and / or etching recipe stage. In some embodiments, the recipe stages may be arranged in sequence so that all instructions for a process stage are executed simultaneously with that process stage.

[0193] In some embodiments, other computer readable instructions and / or programs stored on a mass storage device 554 and / or a memory device 556 associated with the system controller 550 may be employed. Examples of programs or program segments include substrate positioning programs, process gas control programs, pressure control programs, heater control programs, and plasma control programs.

[0194] The substrate positioning program may include instructions for a processing tool assembly that is used to load a substrate onto a susceptor and control the spacing between the substrate and other components of the processing tool. The positioning program may include instructions for appropriately moving the substrate into and out of a reaction chamber as needed to deposit and / or etch a film on the substrate.

[0195] The process gas control program may include instructions for controlling gas composition and flow rate and optionally for causing gas to flow to the volume around one or more processing stations before deposition and / or etching to stabilize the pressure in these volumes. In some embodiments, the process gas control program may include instructions for introducing certain gases into the volume around one or more processing stations in the processing chamber during deposition and / or etching operations on the substrate. The process gas control program may also include instructions for delivering these gases at the same rate during the same period, or at different rates and / or during different periods, depending on the composition of the film to be deposited and / or the characteristics of the etching process involved. The process gas control program may also include instructions for atomizing / vaporizing liquid reactants in the presence of helium or some other carrier gases in a heated injection module.

[0196] The pressure control program may include instructions for controlling the pressure within the process station by adjusting, for example, a throttle valve in an exhaust system of the process station, gas flow into the process station, etc. The pressure control program may include instructions for maintaining the same or different pressures during deposition of various types of films on a substrate and / or etching of a substrate.

[0197] The heater control program may include instructions for controlling the flow of current to a heating unit for heating the substrate. Alternatively or additionally, the heater control program may control the delivery of a heat transfer gas (such as helium) toward the substrate. The heater control program may include instructions for maintaining the same or different temperatures within a reaction chamber and / or a volume surrounding a processing station during deposition of various types of films on the substrate and / or etching of the substrate.

[0198] The plasma control program may include instructions for setting RF power levels, frequencies, and exposure times within one or more processing stations according to embodiments of the present invention. In some embodiments, the plasma control program may include instructions for using the same or different RF power levels and / or frequencies and / or exposure times during deposition of a film on a substrate and / or etching of a substrate.

[0199] In some embodiments, there may be a user interface associated with the system controller. The user interface may include a display screen, a graphical software display of apparatus and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0200] In some embodiments, the parameters adjusted by the system controller may relate to process conditions. Non-limiting examples include process gas composition and flow rate, temperature (e.g., substrate holder and showerhead temperature), pressure, plasma conditions (e.g., RF bias power level and exposure times), etc. These parameters may be provided to the user in the form of a recipe, which may be entered using the user interface.

[0201] Signals for monitoring the process can be provided from various process tool sensors by analog and / or digital input connections of the system controller. Signals for controlling the process can be output by analog and / or digital output connections of the process tool. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers (MFCs), pressure sensors (e.g., manometers), temperature sensors such as thermocouples, and the like. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

[0202] The various apparatus and methods described above may be used in conjunction with lithography patterning tools and / or processes, for example, to manufacture or produce semiconductor devices, displays, light emitting diodes, photovoltaic panels, etc. Typically, but not necessarily, such tools would be used together and / or simultaneously in a common manufacturing facility, or such processes would be performed together and / or simultaneously in a common manufacturing facility.

[0203] In some embodiments, the controller is part of a system, and a part of the system can be part of the above-mentioned embodiments. Such a system can include a semiconductor processing device, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer bases, gas flow systems, etc.). These systems can be integrated with electronic devices to control the operation of these systems before, during, or after the processing of semiconductor wafers or substrates. Electronic devices can be referred to as "controllers", which can control various components or sub-parts of one or more systems. Depending on the processing requirements and / or the type of system, the controller can be programmed to control any of the processes disclosed in the present invention, including controlling the delivery of process gases, the setting of temperature (e.g., heating and / or cooling), the setting of pressure, the setting of vacuum, the setting of power, the setting of radio frequency (RF) generators, the setting of RF matching circuits, the setting of frequencies, the setting of flow rates, the setting of fluid delivery, the setting of positions and operations, the delivery of wafer entry and exit tools and other delivery tools and / or the delivery of load locks connected to or interfaced with a specific system.

[0204] Broadly speaking, a controller can be defined as an electronic device with various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit may include a chip storing program instructions in the form of firmware, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions may be instructions that communicate with the controller in the form of various individual settings (or program files), which define operating parameters on or for a semiconductor wafer or for a specific treatment of the system. In some embodiments, the operating parameters may be a part of a recipe for one or more processing steps in the manufacturing process of one or more (kinds) of a wafer, a material, a metal, an oxide, silicon, silicon dioxide, a surface, a circuit, and / or a die defined by a process engineer.

[0205] In some embodiments, the controller can be a part of or coupled to a computer that is integrated with the system, coupled, or connected to the system or a combination thereof through a network. For example, the controller can be in the "cloud" or all or part of a wafer factory (fab) host system, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current processing of manufacturing operations, check the history of past manufacturing operations, check the trends or performance standards of multiple manufacturing operations, change the parameters of the current processing, set the processing steps to follow the current processing or start a new process. In some instances, a remote computer (e.g., a server) can provide a process recipe to the system through a network, which can include a local network or the Internet. The remote computer can include a user interface that allows input or programming parameters and / or settings, which are then transmitted from the remote computer to the system. In some instances, the controller receives instructions in the form of data, which specify the parameters of each processing step to be performed during one or more operations. It should be understood that these parameters can be for the type of process to be performed and the type of tool, and the controller is configured to connect or control the tool type. Thus, as described above, the controller may be distributed, for example, by including one or more discrete controllers that are networked together and work toward a common goal (e.g., the process and control described herein). Examples of distributed controllers for these purposes may be one or more integrated circuits within a chamber that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer) that combine to control the process within the chamber.

[0206] Example systems may include, but are not limited to, plasma etch chambers or modules (using inductively or capacitively coupled plasma), deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfer edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the preparation and / or manufacture of semiconductor wafers.

[0207] As described above, depending on one or more process steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, combination tools, other tool interfaces, adjacent tools, adjacent tools, tools located throughout the factory, a host computer, another controller, or tools used in material handling to move containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0208] Photolithography patterning

[0209] The apparatus / process described herein can be used in conjunction with a photolithographic patterning tool or process, for example, to manufacture or prepare semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, although not necessarily, such tools / processes will be used or performed together in a common manufacturing facility. Photolithographic patterning of films typically includes some or all of the following steps, each of which can be performed using a variety of available tools: (1) applying a photoresist to a workpiece, i.e., a substrate, using a spin coating or spray coating tool; (2) curing the photoresist using a hot plate or oven or a UV curing tool; (3) exposing the photoresist to visible light or ultraviolet light or X-rays using a tool such as a wafer stepper; (4) developing the resist so that it can be selectively removed using a tool such as a wet bench to pattern it; (5) transferring the resist pattern to an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

[0210] Other Implementations

[0211] Although the aforementioned disclosed processes, methods, systems, and devices have been described in detail in the context of specific embodiments for the purpose of promoting clarity and understanding, it is obvious to those skilled in the art that there are many alternative ways of implementing these processes, methods, systems, and devices that fall within the scope and spirit of the invention. Therefore, the embodiments described in the present invention should be regarded as illustrating the creative concepts disclosed in the present invention, rather than limiting or restricting them, and should not be used as an impermissible basis for improperly limiting the scope of the appended claims.

Claims

1. A plasma processing apparatus for reducing metal oxides present on the surface of a metal seed layer of a semiconductor substrate in preparation for a subsequent electroplating operation, the plasma processing apparatus comprising: - a processing chamber, within which there is at least one processing station; - a substrate holder configured to hold a substrate at the processing station; - a plasma generator configured to generate plasma within the process chamber and / or to provide the plasma to the process chamber; - a color sensor configured to measure a color signal from the substrate, the color signal having one or more color components; and - a controller having non-transitory computer readable instructions for: - operating the plasma generator to generate plasma within the processing chamber and / or to provide the plasma to the processing chamber such that the plasma contacts a surface of a substrate at the processing station to process the surface by reducing a metal oxide on the surface; - after the plasma contacts a surface of the substrate, operating the color sensor to measure a post-plasma contact color signal from the surface, the color signal having one or more color components; as well as - estimating the extent of reduction of the oxide due to the plasma treatment based on the color signal after the plasma exposure, Wherein estimating the extent of reduction of the oxide due to the plasma treatment comprises comparing the color signal after the plasma exposure to one or more reference color signals.

2. The plasma processing apparatus of claim 1, wherein the color sensor is positioned and / or configured to measure the color signal from the substrate while the substrate is located at the processing station.

3. The plasma processing apparatus according to claim 1, further comprising: - a load lock configured to provide substrate access to the process chamber; as well as Wherein the color sensor is positioned and / or configured to measure the color signal from the substrate while the substrate is within the load lock.

4. The plasma processing apparatus according to claim 1, wherein: The color sensor is configured to measure a color signal having a b* color component.

5. The plasma processing apparatus according to claim 4, wherein: Estimating the extent of reduction of the oxide due to the plasma treatment is performed based on the b* component of the color signal after the plasma exposure.

6. The plasma processing apparatus of claim 1 , wherein estimating the extent of reduction of the oxide due to the plasma processing comprises: - calculating one or more metrics, each of said metrics being indicative of a difference between said post-plasma contact color signal and a reference color signal from a set of one or more reference color signals.

7. The plasma processing apparatus according to claim 6, wherein: The color sensor is configured to measure a color signal having a b* color component, and Each metric is monotonically related to the absolute value of the difference between the b* component of the post-plasma contact color signal and the b* component of the reference color signal.

8. The plasma processing apparatus according to claim 1, wherein: The controller also has other non-transitory computer readable instructions for operating the color sensor prior to plasma contact to measure a pre-plasma contact color signal from the surface, the color signal having one or more color components, and Estimating the extent of oxide reduction due to plasma treatment involves comparing the color signal before and after plasma exposure.

9. The plasma processing apparatus according to claim 7, wherein: The comparison is done based on the b* component of the color signal.

10. The plasma processing apparatus according to claim 7, wherein: Estimating the extent of oxide reduction due to the plasma treatment includes calculating a metric indicative of a difference between a color signal before and after plasma exposure.

11. The plasma processing apparatus according to claim 10, wherein: The metric is monotonically related to the absolute value of the difference between the b* component of the color signal before and after plasma contact.

12. The plasma processing apparatus according to claim 1, wherein: The plasma generator is configured to generate hydrogen radicals along with the plasma.

13. The plasma processing apparatus according to claim 1, wherein: The metal is copper.

14. The plasma processing apparatus according to claim 1, wherein: The metal is cobalt.

15. The plasma processing apparatus according to claim 1, wherein: The color sensor is configured to be located approximately 0.1-5 inches from the substrate surface during measurement of a post-plasma contact color signal from the surface.

16. The plasma processing apparatus according to claim 15, wherein: The color sensor is configured to be located approximately 0.4-1 inches from the substrate surface during measurement of a post-plasma contact color signal from the surface.

17. The plasma processing apparatus according to claim 10, wherein: The plasma generator is remote from the processing chamber.

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