CN113972126A

CN113972126A - Machining workpieces using oxygen

Info

Publication number: CN113972126A
Application number: CN202110816924.9A
Authority: CN
Inventors: 谢挺
Original assignee: Beijing E Town Semiconductor Technology Co Ltd; Mattson Technology Inc
Current assignee: Beijing E Town Semiconductor Technology Co Ltd; Mattson Technology Inc
Priority date: 2020-07-22
Filing date: 2021-07-20
Publication date: 2022-01-25

Abstract

The present disclosure provides a method for machining a workpiece. The workpiece may include a metal layer. In one exemplary embodiment, the method may include supporting a workpiece on a workpiece support. The method may include subjecting the workpiece to a pretreatment process to form a pretreatment layer from at least a portion of the metal layer. The method may further include subjecting the workpiece to a treatment process to form a treated layer from at least a portion of the pretreatment layer. The treatment process may include exposing the workpiece to one or more hydrogen radicals.

Description

Machining workpieces using oxygen

Technical Field

The present disclosure relates generally to semiconductor processing.

Background

Plasma processing is widely used in the semiconductor industry for deposition, etching, resist removal and related processing of semiconductor wafers and other substrates. Plasma sources (e.g., microwave, ECR, induction, etc.) are commonly used in plasma processing to generate high density plasma and reactive species for processing substrates. Post-implant photoresist, post-etch residue, and other mask and/or material removal has been accomplished using a plasma dry strip process. In a plasma dry strip process, neutral particles from a plasma generated in a remote plasma chamber pass through a separation grid into a process chamber to process a substrate, such as a semiconductor wafer.

Disclosure of Invention

Aspects and advantages of embodiments of the present disclosure will be set forth in part in the description which follows or may be learned by practice of the embodiments.

Aspects of the present disclosure relate to a method for machining a workpiece. The method includes placing a workpiece in a process chamber, the workpiece including a metal layer; subjecting the workpiece to a pre-machining process to alter the surface morphology of at least a portion of the metal layer; and subjecting the workpiece to a treatment process by exposing the workpiece to one or more radicals generated using a plasma source to form a treated layer from at least a portion of the metal layer.

Aspects of the present disclosure also relate to a method for processing a workpiece in a processing chamber separated from a plasma chamber by a separation grid. The method comprises the following steps: placing the workpiece in a process chamber, the workpiece comprising a metal layer; passing a pre-treatment process gas into the plasma chamber; generating one or more species from a pre-treatment process gas using a plasma induced in a plasma chamber, wherein the pre-treatment process gas comprises an oxygen-containing gas; filtering the one or more substances with the separation grid to generate a filtered mixture comprising one or more oxygen radicals; exposing the metal layer to the one or more oxygen radicals in the process chamber to alter a surface morphology of the metal layer; and exposing one or more hydrogen radicals to the metal layer to form a treated layer from at least a portion of the metal layer.

These and other features, aspects, and advantages of the various embodiments will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the relevant principles.

Drawings

A detailed discussion of embodiments directed to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended drawings, in which:

FIG. 1 depicts an example treatment process according to conventional techniques;

FIG. 2 depicts an example treatment process according to an example embodiment of the present disclosure;

FIG. 3 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure;

FIG. 4 depicts an example flow diagram of an example processing method according to an example embodiment of the present disclosure;

FIG. 5 depicts an example generation of hydrogen radicals using post-plasma gas injection in accordance with an example embodiment of the present disclosure;

FIG. 6 depicts the generation of hydrogen radicals using an example filament according to an example embodiment of the present disclosure;

FIG. 7 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure;

FIG. 8 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure; and

fig. 9 depicts Rs reduction of a metal layer on a workpiece of an example plasma processing apparatus according to an example embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the embodiments, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the embodiment, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Accordingly, aspects of the present disclosure are intended to encompass such modifications and alterations.

Example aspects of the present disclosure relate to methods for machining a workpiece to form a treated layer from a portion of a metal layer of the workpiece. More specifically, aspects of the present disclosure relate to a method for processing a workpiece, including placing the workpiece in a processing chamber, the workpiece including a metal layer; subjecting the workpiece to a pretreatment process to alter a surface morphology of at least a portion of the metal layer; and subjecting the workpiece to a treatment process by exposing the workpiece to one or more radicals generated using a plasma source to form a process layer from at least a portion of the metal layer. For example, reactive species extracted from the plasma may be used to alter the surface morphology of a portion of a metal layer present on the workpiece, which may improve the interaction of the metal layer on the workpiece with radicals generated in the treatment process.

Plasma processing systems can be used to process substrates to form Integrated Circuits (ICs) or other electronic products. In particular, it is useful for metal processing processes to expose certain structures on a workpiece (e.g., a metal film or layer) to radicals generated by a plasma system. For example, a metal layer on a workpiece may be exposed to free radicals to promote grain growth, contaminant removal, metal reflow, surface passivation, and the like. In such radical treatment processes, the desired result obtained at or on the surface of the treated metal layer is limited by the amount of treatment radicals. For example, the treatment of the metal layer may be proportional to the flux of radicals generated by the system or the amount of radicals reaching the wafer surface. In particular, if fewer radicals are generated, fewer radicals may be used to treat the metal surface. Also, if fewer radicals are able to contact the wafer surface, the metal surface may not achieve the desired processing.

Thus, methods for improving the performance of radical-based plasma processing processes focus on the efficiency of radical generation and the efficiency of radical delivery from a source to a workpiece. For example, certain metal treatment processes include the use of higher RF power for better radical generation efficiency. Other solutions have proposed reducing the distance of the workpiece from the radical source to improve the transport efficiency. However, these solutions are not always easy to implement in view of the hardware limitations of plasma processing equipment. For example, for some processing equipment, it may not be possible to move the workpiece closer to the radical source, or it may not be possible to increase the power to generate more radicals. Accordingly, there is a need for improved processes for treating workpieces, particularly metal layers on workpieces.

Example aspects of the present disclosure relate to a method for machining a workpiece having a metal layer thereon. The method includes placing a workpiece in a process chamber and subjecting the workpiece to a pretreatment process to alter a surface morphology of at least a portion of the metal layer. The method also includes subjecting the workpiece to a treatment process by exposing the workpiece to one or more radicals generated using a plasma source to form a treated layer from at least a portion of the metal layer. In this way, the pre-treatment process prepares the metal layer, thereby improving the results obtained from the treatment process.

In particular, the pretreatment processes provided herein alter the surface morphology of at least a portion of a metal layer on a workpiece. This surface morphology change may increase the surface area of the metal layer, allowing a greater percentage of the metal layer to be contacted by radicals during the treatment process. For example, in some embodiments, the pretreatment process adjusts a surface-to-volume ratio (surface-to-volume ratio) of the metal layer. The pretreatment process may also produce one or more rounded structures on at least a portion of the metal layer. For example, the preprocessing process increases the available surface area to help process the interaction of the radicals with the metal layer. The pretreatment process may alter the surface composition of at least a portion of the metal layer. For example, the pretreatment process may increase the oxygen dose at the surface of the metal layer, which may reduce energy during the formation of metal grains that react with H radicals.

The pretreatment process described herein can include generating one or more species or radicals from a pretreatment process gas using a plasma induced in a plasma chamber. The pre-treatment process gas may comprise an oxygen-containing gas. The process can include filtering the one or more species to produce a filtered mixture comprising one or more oxygen radicals. The process includes exposing the metal layer to one or more oxygen radicals in a process chamber, such that the oxygen radicals alter a surface morphology of at least a portion of the metal layer. In certain other embodiments, the pretreatment process may include exposing the workpiece to a high temperature oxygen-containing gas to alter the surface morphology of the metal layer.

Aspects of the present disclosure provide a number of technical effects and benefits. For example, the processes disclosed herein allow for the modification of the surface morphology of a metal layer or film on a workpiece. This change increases the surface to volume ratio of the metal layer, which corresponds to an increase in the interaction volume of the metal layer with the incoming radicals during the treatment process. Increasing the surface to volume ratio promotes the interaction of process radicals with the metal layer, which results in an increase in the amount of metal layer that is treated. Also, the modification of the surface morphology of the metal layer allows for increased efficiency in the treatment process. Furthermore, the present methods, including the pretreatment process and the treatment process, can be performed in the same process chamber, i.e., in situ, without the need for additional process chambers or other devices.

For purposes of illustration and discussion, aspects of the present disclosure are discussed with reference to a "workpiece," "wafer," or semiconductor wafer. One of ordinary skill in the art, using the disclosure provided herein, will appreciate that example aspects of the disclosure may be used in association with any semiconductor substrate or other suitable substrate. Further, use of the term "about" in conjunction with a numerical value is intended to mean within ten percent (10%) of the numerical value. "susceptor" refers to any structure that can be used to support a workpiece.

Fig. 1 depicts an overview of a treatment process 20 performed on a workpiece 10 without a pretreatment process. As shown, the workpiece 10 includes a substrate 12 and a metal layer 14. After the treatment process 20 is applied, a portion of the metal layer 14 is converted into a treated layer 16. Thus, the treatment process 20 results in the substrate 12 having the metal layer 14 and the treated layer 16 thereon. However, as can be seen in fig. 1, the treated layer 16 may not be very thick given the limited interaction between the one or more treatment radicals and the metal layer 14 during the treatment process 20.

Fig. 2 depicts an overview of a treatment process 20 that includes a pretreatment process 18 as disclosed herein. As shown, the workpiece 10 includes a substrate 12 and a metal layer 14. The workpiece 10 is exposed to a pretreatment process 18 that changes the surface morphology of at least a portion of the metal layer 14 as shown. In fact, the pretreatment process 18 may adjust the surface-to-volume ratio of the metal layer. The pretreatment process 18 may also create one or more rounded structures on the metal layer 14 to increase the available surface area of the metal layer 14.

As shown, after the pre-treatment process 18 is completed, the workpiece 10 is subjected to a treatment process 20. The treatment process 20 may expose the workpiece 10 to one or more radicals generated using a plasma source to form the treated layer 16 from at least a portion of the metal layer 14. When the pretreatment process 18 is performed prior to the treatment process 20, the treated layer 16 on the workpiece 10 may be much thicker in view of the increased interaction between the one or more treatment radicals and the metal layer 14 during the treatment process. Again, this increased interaction is facilitated by performing a pretreatment process 18 that alters the surface morphology of the metal layer 14. This increase in the surface area of the metal layer 14 allows for greater interaction between the metal layer 14 and the process radicals during the treatment process 20, which corresponds to the presence of more of the treated layer 16 on the workpiece 10.

Fig. 3 depicts an example plasma processing apparatus 100 that may be used to perform a process according to an example embodiment of the present disclosure. As shown, plasma processing apparatus 100 includes a process chamber 110 and a plasma chamber 120 separate from process chamber 110. The process chamber 110 includes a workpiece support or pedestal 112 operable to hold a workpiece 114, such as a semiconductor wafer, to be processed. In this exemplary illustration, a plasma is generated in plasma chamber 120 (i.e., the plasma generation region) by inductively coupled plasma source 135, and the desired species are directed from plasma chamber 120 to the surface of substrate 114 through separation grid assembly 200.

For purposes of illustration and discussion, aspects of the present disclosure are discussed with reference to an inductively coupled plasma source. One of ordinary skill in the art, using the disclosure provided herein, will appreciate that any plasma source (e.g., inductively coupled plasma source, capacitively coupled plasma source, etc.) may be used without departing from the scope of the present disclosure.

The plasma chamber 120 includes dielectric sidewalls 122 and a ceiling 124. The dielectric sidewalls 122, top plate 124, and separation grid 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material such as quartz and/or alumina. Inductively coupled plasma source 135 may include an induction coil 130, with induction coil 130 disposed about dielectric sidewall 122 about plasma chamber 120. The inductive coil 130 is coupled to an RF power generator 134 through a suitable matching network 132. A process gas (e.g., hydrogen or ozone gas) can be provided to the chamber interior from a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include an optional grounded faraday shield 128 to reduce capacitive coupling of the inductive coil 130 to the plasma.

As shown in fig. 3, a separation grid 200 separates the plasma chamber 120 from the process chamber 110. Separation grid 200 may be used to perform ion filtration on a mixture generated from a plasma in plasma chamber 120 to generate a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber 110.

In some embodiments, the separation grid 200 may be a multi-plate separation grid. For example, the separation grid 200 may include a first grid plate 210 and a second grid plate 220 spaced parallel to each other. The first grid plate 210 and the second grid plate 220 may be separated by a distance.

The first grid plate 210 may have a first grid pattern with a plurality of apertures. The second grid plate 220 may have a second grid pattern with a plurality of apertures. The first grid pattern may be the same as or different from the second grid pattern. The charged particles may recombine on the wall in their path through the apertures of each

grid plate

210, 220 in the separation grid. Neutral species (e.g., radicals) may flow relatively freely through the apertures in the first grid plate 210 and the second grid plate 220. The size of the apertures and the thickness of each

grid plate

210 and 220 can affect the transparency of both the charged and neutral particles.

In some embodiments, first grid plate 210 may be made of metal (e.g., aluminum) or other electrically conductive material, and/or second grid plate 220 may be made of electrically conductive or dielectric material (e.g., quartz, ceramic, etc.). In some embodiments, first grid plate 210 and/or second grid plate 220 may be made of other materials (e.g., silicon or silicon carbide). In the case of a grid plate made of metal or other electrically conductive material, the grid plate may be grounded. In some embodiments, the grate assembly may comprise a single grate having one grate plate.

As shown in fig. 3, according to an example aspect of the disclosure, the apparatus 100 may include a gas delivery system 150 configured to deliver one or more process gases to the plasma chamber 120, for example, through a gas distribution channel 151 or other distribution system (e.g., a showerhead). The gas delivery system can include a plurality of feed gas lines 159. The feed gas line 159 can be controlled using a valve 158 and/or a mass flow controller to deliver a desired amount of gas as a process gas into the plasma chamber. As shown in FIG. 3, the gas delivery system 150 may include a system for delivering a hydrogen-containing gas (e.g., H)₂、CH₄Or NH₃) And/or for conveying an oxygen-containing gas (e.g. O)₂NO or CO₂) The feed gas line of (2). In some embodiments, the hydrogen-containing gas and/or the oxygen-containing gas may be mixed with an inert gas such as He, Ar, N, which may be referred to as a "carrier" gas₂Ne and/or Xe. Control valves and/or mass flow controllers 158 may be used to control the flow rate of each feed gas line to flow process gas into the plasma chamber 120.

Fig. 4 depicts a flowchart of an example method (300) according to an example aspect of the present disclosure. The method (300) will be discussed, by way of example, with reference to the plasma processing apparatus 100 of fig. 3. The method (300) may be implemented in any suitable plasma processing apparatus. Fig. 4 depicts steps performed in a particular order for purposes of illustration and discussion. One of ordinary skill in the art, using the disclosure provided herein, will appreciate that the various steps of any method described herein may be omitted, expanded, performed concurrently, rearranged and/or modified in various ways without departing from the scope of the present disclosure. In addition, various steps (not shown) may be performed without departing from the scope of the present disclosure.

At (302), the method can include placing a workpiece 114 in a process chamber 110 of a plasma processing apparatus 100. The workpiece 114 includes one or more metal layers. For example, the workpiece 114 may include a metal layer comprising copper. Process chamber 110 can be separated from plasma chamber 120 (e.g., by a separation grid assembly). For example, the method may include placing the workpiece 114 on the workpiece support 112 in the process chamber 110.

At (304), the method may include subjecting the workpiece to a pretreatment process to alter a surface morphology of at least a portion of the metal layer. The pretreatment process can adjust the surface to volume ratio of the metal layer. The pretreatment process may also produce one or more rounded structures on at least a portion of the metal layer. The pretreatment process may also alter the surface composition of at least a portion of the metal layer.

The pretreatment process may include generating one or more species from the process gas. One or more species may be generated using a plasma induced in a plasma chamber. The pre-treatment process may include passing a process gas into the plasma chamber 120. For example, process gases may be introduced into the plasma chamber interior 125 from the gas source 150 through an annular gas distribution channel 151 or other suitable gas introduction mechanism. In some embodiments, the process gas may include an oxygen-containing gas.

The process gas is energized by an inductively coupled plasma source to generate a plasma in the plasma chamber 120. For example, the inductive coil 130 can be energized with RF energy from the RF power generator 134 to generate a plasma in the plasma chamber interior 125. In some embodiments, an inductively coupled plasma source may be energized with pulsed power to obtain desired radicals of reduced plasma energy. In some embodiments, the inductively coupled plasma source may be operated at a power in a range of about 0W to about 2500W. The plasma may be used to generate one or more oxygen radicals from an oxygen-containing process gas.

The pre-treatment process (304) may include filtering one or more ions generated by the plasma to generate a filtered mixture. The filtered mixture may contain neutral oxygen radicals. In some embodiments, one or more ions may be filtered using a separation grid assembly 200 that separates the plasma chamber 120 from the process chamber 110 in which the workpiece is located. For example, the separation grid assembly 200 may be used to filter ions generated by a plasma. The separation gate 200 may have a plurality of holes. Charged particles (e.g., ions) may recombine on the walls in their path through the plurality of pores. Neutral species (e.g., radicals) can pass through the pores.

In some embodiments, the separation grid 200 can be configured to filter ions with an efficiency of greater than or equal to about 90%, such as greater than or equal to about 95%. The percent efficiency of ion filtration refers to the proportion of the amount of ions removed from the mixture relative to the total number of ions in the mixture. For example, an efficiency of about 90% indicates that about 90% of the ions are removed during filtration. An efficiency of about 95% indicates that about 95% of the ions are removed during filtration.

In some embodiments, the separation grid 200 may be a multi-plate separation grid. The multi-plate separation grid may have a plurality of parallel separation grid plates. The arrangement and alignment of the apertures in the grid plate can be selected to provide a desired ion filtration efficiency, such as greater than or equal to about 95%.

For example, the separation grid 200 may have a first grid plate 210 and a second grid plate 220 that are parallel to each other. The first grid plate 210 may have a first grid pattern with a plurality of apertures. The second grid plate 220 may have a second grid pattern with a plurality of apertures. The first grid pattern may be the same as or different from the second grid pattern. Charged particles (e.g., ions) may recombine on the walls in their path through the apertures of each

grid plate

210, 220 in the separation grid 200. Neutral species (e.g., radicals) may flow relatively freely through the apertures in the first grid plate 210 and the second grid plate 220.

The pretreatment process (304) may include exposing the workpiece to one or more radicals including oxygen radicals. More specifically, the workpiece may be exposed to oxygen radicals generated in the plasma and passing through the separation grid assembly. As an example, oxygen radicals may pass through the separation grid 200 and be exposed to the workpiece 114. Exposing the workpiece to oxygen radicals may change a surface morphology of at least a portion of the metal layer. The pretreatment process may be conducted at a process temperature of about 70 ℃ to about 400 ℃.

In certain embodiments, the pretreatment process may include exposing the workpiece to an oxygen-containing gas at a temperature of about 70 ℃ to about 400 ℃. For example, in some embodiments, the pretreatment process may include exposing the metal layer to an oxygen-containing gas. In such embodiments, the oxygen-containing gas may be delivered to the plasma chamber 120 and may pass through the separation grid 200 to the workpiece. For example, an oxygen-containing gas may be delivered into the plasma chamber 120 through a suitable gas supply 150 and annular gas distribution channel 151. In some embodiments, the oxygen-containing gas may be delivered into the process chamber 110 through the separation grid 200 or below the separation grid 200 so that the oxygen-containing gas is injected downstream of the plasma source. The workpiece 114 may include a metal layer. The oxygen-containing gas may react with the exposed surface of the metal layer to alter the surface morphology of the metal layer of the workpiece 114.

At (306), the method may include subjecting the workpiece to a treatment process to form a treated layer from at least a portion of the metal layer. The treatment process may include a hydrogen radical treatment process. Treating the metal layer with a hydrogen radical treatment process may remove contaminants in the metal layer, increase the grain size of the metal layer, or reflow the metal layer to fill any seams or gaps. The hydrogen radical treatment process may include passing a process gas (e.g., a treatment process gas) into plasma chamber 120. For example, process gases may be introduced into the plasma chamber interior 125 from the gas source 150 through an annular gas distribution channel 151 or other suitable gas introduction mechanism. In some embodiments, the process gas may include hydrogen. In some embodiments, the process gas comprises a hydrogen-containing gas, such as H₂。

The process gas is energized by the inductively coupled plasma source to generate a plasma in the plasma chamber 120. For example, the inductive coil 130 can be energized with RF energy from an RF power generator 134 to generate a plasma 125 inside the plasma chamber. In some embodiments, an inductively coupled plasma source may be energized with pulsed power to obtain desired radicals of reduced plasma energy. In some embodiments, the inductively coupled plasma source may be operated at a power in the range of about 400W to about 5000W. The plasma may be used to generate one or more hydrogen radicals from the hydrogen process gas.

The hydrogen radical treatment process (306) may include filtering one or more ions generated by the plasma to produce a filtered mixture. The filtered mixture may contain neutral hydrogen radicals. In some embodiments, one or more ions may be filtered using a separation grid assembly 200 that separates the plasma chamber 120 from the process chamber 110 in which the workpiece is located. For example, the separation grid assembly 200 may be used to filter ions generated by a plasma. The separation gate 200 may have a plurality of holes. Charged particles (e.g., ions) may recombine on the walls in their path through the plurality of pores. Neutral species (e.g., radicals) can pass through the pores.

grid plate

The hydrogen radical treatment process 306 may include exposing the workpiece to hydrogen radicals. More specifically, the workpiece may be exposed to hydrogen radicals generated in the plasma and passing through the separation grid assembly. As an example, hydrogen radicals may pass through separation grid 200 and be exposed to workpiece 114. Exposing the workpiece to hydrogen radicals can result in a process layer being formed from at least a portion of the metal layer of the workpiece.

The hydrogen radical treatment process (306) may be carried out by generating hydrogen radicals using other methods without departing from the scope of the present disclosure. For example, in some embodiments, hydrogen radicals may be generated at least in part using a post-plasma gas injection (as discussed with reference to fig. 5) and/or a heated filament (see fig. 6).

In some embodiments, the treatment process may include exposing the workpiece to a process gas. The workpiece may be exposed to a process gas having a temperature of about 70 ℃ to about 400 ℃. For example, in some embodiments, the treatment process may include exposing the metal layer to a hydrogen-containing gas. In such embodiments, the hydrogen-containing gas may be delivered to the plasma chamber 120 and may pass through the separation grid 200 to the workpiece. For example, a hydrogen-containing gas may be delivered into the plasma chamber 120 through a suitable gas supply 150 and annular gas distribution channel 151. In some embodiments, the hydrogen-containing gas may be delivered into the process chamber 110 through the separation grid 200 or below the separation grid 200 such that the hydrogen-containing gas is injected downstream of the plasma source. The workpiece 114 may include a metal layer. The hydrogen-containing gas may react with the exposed surface of the metal layer to alter the surface morphology of the metal layer on the workpiece 114.

At (308), the method may include removing the workpiece from the process chamber. For example, the workpiece 114 can be removed from the workpiece support 112 in the process chamber 110. The plasma processing apparatus can then be adjusted for future processing of other workpieces.

Fig. 5 depicts an example generation of hydrogen radicals using post-plasma gas injection in accordance with an example embodiment of the present disclosure. More specifically, fig. 5 depicts an example separation grid 200 for post-plasma hydrogen implantation in accordance with example embodiments of the present disclosure. More specifically, the separation fence 200 includes a first grid plate 210 and a second grid plate 220 arranged in parallel. The first grid plate 210 and the second grid plate 220 may provide ion/UV filtration.

The first and

second grid plates

210 and 220 may be parallel to each other. The first grid plate 210 may have a first grid pattern with a plurality of apertures. The second grid plate 220 may have a second grid pattern with a plurality of apertures. The first grid pattern may be the same as or different from the second grid pattern. Species (e.g., excited noble gas molecules) 215 from the plasma may be exposed to the separation grid 200. Charged particles (e.g., ions) may recombine on the walls in their path through the apertures of each

grid plate

210, 220 in the separation grid 200. Neutral species may flow relatively freely through the apertures in the first and

second grid plates

210, 220.

After the second grid plate 220, the gas injection source 230 may be configured to mix hydrogen 232 into the substance passing through the separation grid 200. A mixture 225 containing hydrogen radicals generated by the implantation of hydrogen gas can pass through the third grid plate 235 to be exposed to the workpiece in the process chamber.

For purposes of example, the present example is discussed with reference to a separation grid having three grid plates. One of ordinary skill in the art, using the disclosure provided herein, will appreciate that more or fewer grating plates may be used without departing from the scope of the present disclosure. Furthermore, the hydrogen may be mixed with the substance in the process chamber at any point in the separation grid and/or after the separation grid. For example, gas injection source 230 may be located between first grid plate 210 and second grid plate 220.

In some embodiments, hydrogen radicals may be generated by passing hydrogen gas through a heated filament (e.g., a tungsten filament). For example, as shown in FIG. 6, hydrogen H ₂240 may be passed through a heated filament 245, such as a tungsten filament, to generate hydrogen radicals 225 in the first chamber. Hydrogen radicals 225 may pass through separation grid 200.

The separation grill 200 includes a first grill plate 210 and a second grill plate 220 arranged in parallel. The first grid plate 210 may have a first grid pattern with a plurality of apertures. The second grid plate 220 may have a second grid pattern with a plurality of apertures. The first grid pattern may be the same as or different from the second grid pattern.

Other plasma processing apparatuses may be used to implement the methods provided herein without departing from the scope of the present disclosure.

Fig. 7 depicts an example plasma processing apparatus 500 that may be used to implement a process according to example embodiments of the present disclosure. The plasma processing apparatus 500 is similar to the plasma processing apparatus 100 of fig. 3.

More specifically, plasma processing apparatus 500 includes a process chamber 110 and a plasma chamber 120 separate from process chamber 110. The process chamber 110 includes a substrate holder or pedestal 112 operable to hold a workpiece 114, such as a semiconductor wafer, to be processed. In this exemplary illustration, a plasma is generated in plasma chamber 120 (i.e., the plasma generation region) by inductively coupled plasma source 135, and the desired species are directed from plasma chamber 120 to the surface of substrate 114 through separation grid assembly 200.

The plasma chamber 120 includes dielectric sidewalls 122 and a ceiling 124. The dielectric sidewalls 122, top plate 124, and separation grid 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material such as quartz and/or alumina. Inductively coupled plasma source 135 may include an induction coil 130, with induction coil 130 disposed about dielectric sidewall 122 about plasma chamber 120. The inductive coil 130 is coupled to an RF power generator 134 through a suitable matching network 132. Process gas (e.g., inert gas) may be provided to the chamber interior from a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include an optional grounded faraday shield 128 to reduce capacitive coupling of the inductive coil 130 to the plasma.

As shown in fig. 7, a separation grid 200 separates the plasma chamber 120 from the process chamber 110. The separation grid 200 can be used to perform ion filtration on a mixture generated by passing a plasma in the plasma chamber 120 to produce a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber 110.

The first grid plate 210 may have a first grid pattern with a plurality of apertures. The second grid plate 220 may have a second grid pattern with a plurality of apertures. The first grid pattern may be the same as or different from the second grid pattern. The charged particles may recombine on the walls in their path through the apertures of each

grid plate

In some embodiments, first grid plate 210 may be made of metal (e.g., aluminum) or other electrically conductive material, and/or second grid plate 220 may be made of electrically conductive or dielectric material (e.g., quartz, ceramic, etc.). In some embodiments, first grid plate 210 and/or second grid plate 220 may be made of other materials (e.g., silicon or silicon carbide). In the case of a grid plate made of metal or other electrically conductive material, the grid plate may be grounded.

As described above, hydrogen gas may be implanted into the substance passing through separation grid 200 to generate one or more hydrogen radicals for exposure to workpiece 114. The hydrogen radicals can be used to implement a variety of semiconductor manufacturing processes.

The example plasma processing apparatus 500 of fig. 7 is operable to generate a first plasma 502 (e.g., a remote plasma) in the plasma chamber 120 and a second plasma 504 (e.g., a direct plasma) in the process chamber 110. As used herein, "remote plasma" refers to a plasma generated remotely from a workpiece, such as a plasma generated in a plasma chamber separated from the workpiece by a separation grid. As used herein, "direct plasma" refers to a plasma that is directly exposed to a workpiece, such as a plasma generated in a process chamber having a pedestal operable to support a workpiece.

More specifically, the plasma processing apparatus 500 of fig. 7 includes a bias source having a bias electrode 510 in the susceptor 112. The bias electrode 510 may be coupled to an RF power generator 514 through a suitable matching network 512. When the bias electrode 510 is energized by RF energy, a second plasma 504 may be generated from the mixture in the process chamber 110 for direct exposure to the workpiece 114. The process chamber 110 may include an exhaust port 516 for exhausting gas from the process chamber 110. One or more oxygen radicals used in a pretreatment process and/or hydrogen radicals used in a hydrogen radical treatment process according to example aspects of the present disclosure may be generated using first plasma 502 and/or second plasma 504.

Fig. 8 depicts a plasma processing apparatus 600 similar to the plasma processing apparatus of fig. 2 and 7. More specifically, the plasma processing apparatus 600 includes a process chamber 110 and a plasma chamber 120 separate from the process chamber 110. The process chamber 110 includes a substrate holder or pedestal 112 operable to hold a workpiece 114, such as a semiconductor wafer, to be processed. In this exemplary illustration, a plasma is generated in plasma chamber 120 (i.e., the plasma generation region) by inductively coupled plasma source 135, and the desired species are directed from plasma chamber 120 to the surface of substrate 114 through separation grid assembly 200.

The plasma chamber 120 includes dielectric sidewalls 122 and a ceiling 124. The dielectric sidewalls 122, top plate 124, and separation grid 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material such as quartz and/or alumina. Inductively coupled plasma source 135 may include an induction coil 130, with induction coil 130 disposed about dielectric sidewall 122 about plasma chamber 120. The inductive coil 130 is coupled to an RF power generator 134 through a suitable matching network 132. Process gas (e.g., inert gas) may be provided to the chamber interior by a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include an optional grounded faraday shield 128 to reduce capacitive coupling of the inductive coil 130 to the plasma.

As shown in fig. 8, a separation grid 200 separates the plasma chamber 120 from the process chamber 110. The separation grid 200 can be used to perform ion filtration on a mixture generated by passing a plasma in the plasma chamber 120 to produce a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber.

grid plate

The example plasma processing apparatus 600 of fig. 8 is operable to generate a first plasma 602 (e.g., a remote plasma) in the plasma chamber 120 and a second plasma 604 (e.g., a direct plasma) in the process chamber 110. As shown, the plasma processing apparatus 600 can include an angled dielectric sidewall 622 extending from the vertical sidewall 122 associated with the remote plasma chamber 120. The angled dielectric sidewall 622 can form a portion of the process chamber 110.

A second inductive plasma source 635 may be located near the dielectric sidewall 622. The second inductive plasma source 635 may include an inductive coil 610, the inductive coil 610 being coupled to an RF generator 614 through a suitable matching network 612. The inductive coil 610, when energized with RF energy, can induce a direct plasma 604 from the mixture in the process chamber 110. A faraday shield 628 may be disposed between the induction coil 610 and the sidewall 622.

The base 112 is movable in the vertical direction V. For example, the base 112 may include a vertical lift 616, and the lift 616 may be configured to adjust the distance between the base 112 and the split grate assembly 200. As one example, the pedestal 112 may be located in a first vertical position for processing using the remote plasma 602. The pedestal 112 may be positioned in a second vertical position for processing using the direct plasma 604. The first vertical position may be closer to the separation grill assembly 200 than the second vertical position.

The plasma processing apparatus 600 of fig. 8 includes a bias source having a bias electrode 510 in the susceptor 112. The bias electrode 510 may be coupled to an RF power generator 514 through a suitable matching network 512. The process chamber 110 may include an exhaust port 516 for exhausting gas from the process chamber 110. First plasma 602 and/or second plasma 604 may be used to generate one or more oxygen radicals for use in a pretreatment process and/or one or more hydrogen radicals for use in a hydrogen radical treatment process according to example aspects of the present disclosure.

Exemplary process parameters of the pretreatment process will now be set forth.

Example 1

Process gas: o is₂

Dilution ofGas: ar, He or N₂

The process pressure is as follows: 100mT to 6000mT

Inductively coupled plasma source power: 0W to 2500W

Workpiece temperature: 70 ℃ to 400 DEG C

Process cycle (time): 1 second to 60 seconds.

Gas flow rate of process gas:

gas 1: 100sccm to 10,000sccm

Diluting gas: 0sccm to 20,000sccm

Exemplary process parameters for the treatment process will now be set forth.

Example 2

Process gas: h₂

Diluting gas: ar or He

The process pressure is as follows: 10mT to 2000mT

Inductively coupled plasma source power: 2500W to 5000W

Workpiece temperature: 70 ℃ to 400 DEG C

Process cycle (time): 30 seconds to 600 seconds.

Gas flow rate of process gas:

gas 1: 100sccm to 10,000sccm

Diluting gas: 0sccm to 20,000sccm

Fig. 9 shows that the Rs of the copper layer not exposed to the pretreatment process is reduced compared to the other copper layers exposed to the pretreatment process. An increase in the amount of copper layer treated corresponds to an increase in the decrease in Rs. Without the pretreatment process, the Rs reduction of the copper layer was-13.50%. The% reduction in Rs increased to-14.30% when exposed to a pretreatment process that included exposure to oxygen. The% reduction in Rs increased to-14.60% when exposed to a pretreatment process that included exposure to one or more oxygen radicals. Thus, exposing the copper layer to a pretreatment process that includes exposure to oxygen or oxygen radicals increases the Rs reduction of the copper layer, which results in an increase in the amount of the treated copper layer.

While the present subject matter has been described in detail with respect to specific exemplary embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, as is readily understood by those of ordinary skill in the art, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter.

Claims

1. A method for machining a workpiece, the method comprising:

placing the workpiece in a process chamber, the workpiece comprising a metal layer;

subjecting the workpiece to a pre-treatment process to alter the surface morphology of at least a portion of the metal layer; and

the workpiece is subjected to a treatment process by exposing the workpiece to one or more radicals generated using a plasma source to form a treated layer from at least a portion of the metal layer.

2. The method of claim 1, wherein the pretreatment process adjusts a surface-to-volume ratio of the metal layer.

3. The method of claim 1, wherein the pretreatment process produces one or more rounded structures on at least a portion of the metal layer.

4. The method of claim 1, wherein the pre-treatment process comprises:

generating one or more species from a pre-treatment process gas using a plasma induced in a plasma chamber, the pre-treatment process gas comprising an oxygen-containing gas;

filtering the one or more substances to generate a filtered mixture comprising one or more oxygen radicals; and

exposing the metal layer to the one or more oxygen radicals in the process chamber such that the oxygen radicals alter a surface morphology of at least a portion of the metal layer.

5. The method of claim 1, wherein the metal layer comprises copper.

6. The method of claim 4, wherein the processing chamber is separated from the plasma chamber by a separation grid, and the separation grid is used to filter the one or more substances to generate the filtered mixture.

7. The method of claim 1, wherein the one or more radicals are generated from a process gas using an inductively coupled plasma source.

8. The method of claim 1, wherein the treatment process comprises a hydrogen radical treatment process comprising exposing the workpiece to one or more hydrogen radicals.

9. The method of claim 8, wherein the hydrogen radical treatment process comprises:

generating one or more species from a process gas using a plasma induced in a plasma chamber, the process gas comprising a hydrogen-containing gas;

filtering the one or more substances to generate a filtered mixture comprising one or more hydrogen radicals; and

exposing the workpiece to the one or more hydrogen radicals in the process chamber such that the hydrogen radicals form a treated layer from at least a portion of the metal layer.

10. The method of claim 8, wherein the one or more hydrogen radicals are generated using a tungsten filament.

11. The method of claim 8 wherein the one or more hydrogen radicals are generated by mixing hydrogen gas with one or more energized inert gas molecules downstream of the plasma source.

12. The method of claim 8, wherein the pretreatment process is conducted at a process temperature of about 70 ℃ to about 400 ℃.

13. A method for processing a workpiece in a processing chamber separated from a plasma chamber by a separation grid, the method comprising:

passing a pre-treatment process gas into the plasma chamber;

generating one or more species from a pre-treatment process gas using a plasma induced in a plasma chamber, wherein the pre-treatment process gas comprises an oxygen-containing gas;

filtering the one or more substances with the separation grid to generate a filtered mixture comprising one or more oxygen radicals;

exposing the metal layer to the one or more oxygen radicals in the process chamber to alter a surface morphology of the metal layer; and

exposing one or more hydrogen radicals to the metal layer to form a treated layer from at least a portion of the metal layer.

14. The method of claim 13, wherein exposing one or more hydrogen radicals to the metal layer to form a treated layer from at least a portion of the metal layer comprises:

generating one or more species from a process gas comprising hydrogen using a plasma induced in a plasma chamber

exposing the workpiece to the one or more hydrogen radicals in the process chamber such that the filtered mixture forms a treated layer from at least a portion of the metal layer.

15. The method of claim 13, wherein the one or more hydrogen radicals are generated using a tungsten filament.

16. A method according to claim 13 wherein the one or more hydrogen radicals are generated by mixing hydrogen gas with one or more excited inert gas molecules downstream of the plasma source.

17. The method of claim 13, wherein the metal layer comprises copper.

18. The method of claim 13, wherein the pretreatment process is conducted at a process temperature of about 70 ℃ to about 400 ℃.

19. The method of claim 13, wherein exposing the metal layer to the one or more oxygen radicals in the process chamber to change a surface morphology of the metal layer adjusts a surface-to-volume ratio of the metal layer.

20. The method of claim 13, wherein exposing the metal layer to the one or more oxygen radicals in the process chamber to change a surface morphology of the metal layer creates one or more rounded structures on at least a portion of the metal layer.