CN111524872B - Monitoring method for removing copper oxide in copper interconnection NDC (non-copper interconnect) process - Google Patents
Monitoring method for removing copper oxide in copper interconnection NDC (non-copper interconnect) process Download PDFInfo
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- CN111524872B CN111524872B CN202010359959.XA CN202010359959A CN111524872B CN 111524872 B CN111524872 B CN 111524872B CN 202010359959 A CN202010359959 A CN 202010359959A CN 111524872 B CN111524872 B CN 111524872B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
- H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
- H01L23/528—Geometry or layout of the interconnection structure
- H01L23/5283—Cross-sectional geometry
Abstract
The invention relates to the technical field of semiconductor manufacturing, in particular to a monitoring method for removing copper oxide in a copper interconnection NDC (non-volatile semiconductor) manufacturing process. The method at least comprises the following steps: forming an interconnect structure including copper interconnect lines; exposing the copper oxide on the surface of the copper interconnection line in the processing space; introducing ammonia gas into the treatment space, so that the ammonia gas forms ammonia plasma in the treatment space, and the ammonia plasma can remove copper oxide on the surface of the copper interconnection line; the ammonia plasma that has not reacted with the copper oxide is dissociated in the processing space to form hydrogen ions; acquiring hydrogen ion concentration information in real time; determining the reaction degree of the copper oxide according to the hydrogen ion concentration information; when the reaction degree of the copper oxide is completely removed, the ammonia gas is stopped from being introduced into the treatment space. By monitoring the concentration of hydrogen ions and judging the reaction degree of copper oxide, the problem that more hillock-shaped bulges are formed due to the fact that the surface of the copper interconnection line is in a compressive stress state due to overlong ammonia plasma processing time in the related technology can be solved.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to a monitoring method for removing copper oxide in a copper interconnection NDC (non-volatile semiconductor) manufacturing process.
Background
With the development of semiconductor manufacturing processes, the area of a semiconductor chip is smaller and smaller, and the number of semiconductor devices on one semiconductor chip is also larger and larger. In semiconductor circuits, high density of metal interconnects are required for signal transmission between semiconductor devices, however, the large resistance and parasitic capacitance associated with these metal interconnects may limit the speed of the semiconductor circuits.
Since a Nitride Doped Silicon Carbide (NDC) layer has good isolation and etching selectivity, it is often used as a dielectric barrier layer in copper interconnection technology to prevent metal copper from diffusing into the dielectric. However, the surface of the copper interconnect is very susceptible to oxidation, and a layer of copper oxide is formed on the exposed surface of the copper interconnect, which increases the interconnect resistance.
The related art generally treats the surface of copper by ammonia plasma, removes copper oxide on the surface of the copper interconnection line by the reducibility of ammonia, and forms a CuNx compound at a copper grain boundary, however, the CuNx compound under the action of the plasma makes the surface of the copper interconnection line in a compressive stress state, which further causes the formation of more hillock (hillock), thereby affecting the yield of the device.
Therefore, the method can reduce the hillock-shaped protrusion on the surface of the copper interconnection line on the premise that the copper oxide on the surface of the copper interconnection line is completely removed before the dielectric barrier layer is formed.
Disclosure of Invention
The invention provides a monitoring method for removing copper oxide in a copper interconnection NDC (non-dispersive copper-based interconnect) manufacturing process, which can solve the problem that more hillock-shaped bulges are formed because the surface of a copper interconnection line is in a compressive stress state due to overlong ammonia plasma processing time in the related technology.
In one aspect, an embodiment of the present invention provides a method for monitoring removal of copper oxide in a copper interconnection NDC process, where the method at least includes the following steps:
forming an interconnect structure including copper interconnect lines;
exposing the copper oxide on the surface of the copper interconnection line in a processing space;
introducing ammonia gas into the treatment space, so that the ammonia gas forms ammonia plasma in the treatment space, and the ammonia plasma can remove the copper oxide on the surface of the copper interconnection line;
the ammonia plasma that does not react with the copper oxide is dissociated in the processing space to form hydrogen ions;
acquiring hydrogen ion concentration information in real time;
determining the reaction degree of the copper oxide according to the hydrogen ion concentration information;
and when the reaction degree of the copper oxide is completely removed, stopping introducing ammonia gas into the treatment space.
Optionally, the ammonia gas is introduced into the treatment space, and the flow of the introduced ammonia gas is 500-5000 sccm.
Optionally, the environment of the processing space includes: the pressure of the processing space is set to 1 to 4 Torr.
Optionally, the environment of the processing space further includes: the radio frequency power in the processing space is 100-800W.
Optionally, the environment of the processing space further includes: and the radio frequency power in the processing space is 13-14 MHz.
Optionally, the determining the reaction degree of the copper oxide according to the hydrogen ion concentration information includes:
determining a concentration difference between the currently obtained hydrogen ion concentration and a previous hydrogen ion concentration;
and when the concentration difference value is less than a preset threshold value for a preset time, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
Optionally, when the obtained hydrogen ion concentration signal is kept stable for 2-10 s, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
Optionally, when the concentration difference value is less than a preset threshold for a preset time, determining that the copper oxide on the surface of the copper interconnection line is completely removed, including:
and when the concentration difference value is less than a preset threshold value continuously for 2-10 s, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
The technical scheme of the invention at least comprises the following advantages: this application is through monitoring hydrogen ion concentration, judges the reaction degree of cupric oxide to can judge accurately, reliably whether the cupric oxide reacts completely, and in time stop when the cupric oxide reaction is complete, avoid ammonia plasma processing time overlength to lead to forming CuNx compound in copper crystal boundary department, reduce the hillock arch (hillock) of copper interconnect line surface formation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of an interconnect structure for a copper interconnect line provided herein;
FIG. 2 is a graph showing the relationship between the signal intensity and the reaction time collected by the hydrogen ion concentration collector in the present application;
FIG. 3 is a flow chart of a method for monitoring copper oxide removal in a copper interconnect NDC process as provided herein.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; the connection can be mechanical connection or electrical connection; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the related technology, ammonia gas is introduced into a reaction cavity, and when the copper surface is treated by exciting formed ammonia plasma, the copper oxide is generally ensured to be completely reacted in a fixed treatment time, but the scheme is not accurate enough, a CuNx compound is formed at a copper crystal boundary often because the ammonia plasma treatment time is too long, the CuNx compound can enable the surface of a copper interconnection line to be in a pressure stress state so as to form more hillock bulges (hillock), the embodiment of the application provides a method capable of effectively monitoring the thickness of copper oxide on the surface of the copper interconnection line before the deposition of an NDC dielectric layer, the surface of the copper interconnection line is prevented from being excessively treated while the copper oxide is fully removed, so that sufficient binding force between the copper interconnection line and the NDC dielectric layer is ensured, and the hillock bulges on the surface of the copper interconnection line are reduced.
The principle of the application is as follows:
introducing ammonia gas into the reaction cavity at a certain flow rate, exciting the formed ammonia plasma through the plasma action to treat the copper surface, wherein most of the ammonia plasma can react with the copper oxide at the initial stage of the treatment process, so that less free hydrogen ions are dissociated, namely less than 10-10～10-9CM2As the treatment time is prolonged, the remaining unreacted copper oxide is less and less, and the remaining ammonia plasma which is not reacted with the copper oxide is more and more, when the hydrogen ions are maintained for a certain period of time, that is, the copper oxide is completely reacted.
It should be explained that the starting point of the initial phase is defined by the beginning of the enhancement of the collected hydrogen ion concentration signal.
The embodiment provides a method for monitoring removal of copper oxide in a copper interconnection NDC (non-volatile semiconductor) manufacturing process, which at least comprises the following steps:
s1: forming an interconnect structure including copper interconnect lines;
fig. 1 is an interconnection structure of a copper interconnection line, and referring to fig. 1, the interconnection structure comprises a semiconductor substrate layer 100, a copper wiring layer 200 is formed on the semiconductor substrate layer 100, an insulating medium layer 400 is formed on the copper wiring layer 200, the insulating medium layer 400 is etched to form a through hole 310 and a trench 320 positioned on the through hole 310, then the trench 320 and the through hole 310 are filled with copper, excess copper is removed by using a chemical mechanical mask, the insulating medium layer 400 is exposed, and thus the interconnection structure of the copper interconnection line is formed.
S2: exposing the copper oxide on the surface of the copper interconnection line in a processing space;
alternatively, the copper oxide on the surface of the copper interconnect line is exposed in the processing volume by positioning the interconnect structure including the copper interconnect line in the processing volume of the processing chamber.
S3: continuously introducing ammonia gas into the treatment space, so that the ammonia gas forms ammonia plasma in the treatment space, and the ammonia plasma can remove copper oxide on the surface of the copper interconnection line;
wherein the flow rate of the ammonia gas introduced into the processing space is 500-5000 sccm.
The treatment space needs to have a specific environment for the ammonia gas to form the ammonia plasma in the treatment space, and specifically, the environment of the treatment space includes: the pressure of the processing space is 1-4 Torr, the radio frequency power is 100-800W, and the radio frequency is 13.56MHz, and ammonia gas can form ammonia plasma under the environment of the processing space.
S4: the ammonia plasma that does not react with the copper oxide is dissociated in the processing space to form hydrogen ions;
along with the continuous reaction process of the ammonia plasma and the copper oxide, the copper oxide on the surface of the copper interconnection line is gradually reduced, so that the unreacted ammonia plasma is increased, and the concentration of hydrogen ions formed by dissociation of the unreacted ammonia plasma in the processing space is increased; when the copper oxide on the surface of the copper interconnection line is completely reacted, the concentration of hydrogen ions formed by ammonia plasma dissociation is stable.
S5: acquiring hydrogen ion concentration information in real time;
optionally, the exhaust pipeline is communicated with the processing space of the processing chamber through a pendulum valve, the pressure in the processing space is controlled through the pendulum valve, and the hydrogen ion concentration collector is installed between the front-stage pipe and the pendulum valve, so that the hydrogen ion concentration information can be collected and acquired in real time.
S6: determining the reaction degree of the copper oxide according to the hydrogen ion concentration information;
because the copper oxide on the surface of the copper interconnection line is gradually reduced along with the continuous reaction process of the ammonia plasma and the copper oxide, the unreacted ammonia plasma is increased, and the concentration of hydrogen ions formed by dissociation of the unreacted ammonia plasma in the processing space is increased.
Therefore, the reaction degree of the copper oxide can be judged according to the ion concentration information, when the reaction degree of the copper oxide is in the initial state, the hydrogen ions formed by ammonia plasma dissociation are less, the hydrogen ion concentration collected by the hydrogen ion concentration collector is lower, and when the reaction degree of the copper oxide is completely removed, the hydrogen ion concentration collected by the hydrogen ion concentration collector is continuously kept unchanged.
Optionally, the determining the reaction degree of the copper oxide according to the hydrogen ion concentration information includes the following steps:
determining a concentration difference between the currently obtained hydrogen ion concentration and a previous hydrogen ion concentration;
and when the concentration difference value lasts for 2-10 s and is 0, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
Optionally, the determining the reaction degree of the copper oxide according to the hydrogen ion concentration information includes the following steps:
and when the obtained hydrogen ion concentration signal is kept stable for 2-10 s, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
S7: when the reaction degree of the copper oxide is completely removed, the ammonia gas is stopped from being introduced into the treatment space.
The reaction degree of the copper oxide is judged by monitoring the hydrogen ion concentration, so that whether the copper oxide completely reacts can be accurately and reliably judged, the reaction can be stopped in time when the copper oxide completely reacts, CuNx compounds are prevented from being formed at copper crystal boundaries due to overlong ammonia plasma treatment time, and hillock bulges (hillocks) formed on the surface of the copper interconnection line are reduced.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (6)
1. A monitoring method for removing copper oxide in a copper interconnection NDC (non-volatile semiconductor) manufacturing process is characterized by at least comprising the following steps:
forming an interconnect structure including copper interconnect lines;
exposing the copper oxide on the surface of the copper interconnection line in a processing space;
introducing ammonia gas into the treatment space, so that the ammonia gas forms ammonia plasma in the treatment space, and the ammonia plasma can remove the copper oxide on the surface of the copper interconnection line;
the ammonia plasma that does not react with the copper oxide is dissociated in the processing space to form hydrogen ions;
acquiring hydrogen ion concentration information in real time;
determining the reaction degree of the copper oxide according to the hydrogen ion concentration information;
when the reaction degree of the copper oxide is completely removed, stopping introducing ammonia gas into the treatment space;
determining the reaction degree of the copper oxide according to the hydrogen ion concentration information, wherein the step comprises the following steps:
determining a concentration difference between the currently obtained hydrogen ion concentration and a previous hydrogen ion concentration;
and when the concentration difference value is less than a preset threshold value for a preset time, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
2. The method of claim 1, wherein ammonia gas is introduced into the processing volume at a flow rate of 500 to 5000 sccm.
3. The method of claim 1, wherein the environment of the processing volume comprises: the pressure of the processing space is set to 1 to 4 Torr.
4. The method of claim 1, wherein the environment of the processing volume further comprises: and the radio frequency power in the processing space is 13-14 MHz.
5. The method of claim 1, wherein the environment of the processing volume further comprises: the radio frequency in the processing space is 100-800W.
6. The method of claim 1, wherein the determining that the copper oxide on the surface of the copper interconnect line is completely removed when the concentration difference continues for a predetermined time period less than a predetermined threshold comprises:
and when the concentration difference value is less than a preset threshold value continuously for 2-10 s, determining that the copper oxide on the surface of the copper interconnection line is completely removed.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000091620A (en) * | 1998-09-09 | 2000-03-31 | Fujitsu Ltd | Hg-BASED II-VI COMPOUND SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF |
| CN102420173A (en) * | 2011-06-07 | 2012-04-18 | 上海华力微电子有限公司 | Surface treatment method for improving copper interconnection reliability |
| CN102437069A (en) * | 2011-11-30 | 2012-05-02 | 上海华力微电子有限公司 | Method and device for monitoring pretreatment in low-dielectric-constant barrier layer process |
| CN106158727A (en) * | 2015-03-30 | 2016-11-23 | 中芯国际集成电路制造(上海)有限公司 | Copper metallization technology |
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| US6709881B2 (en) * | 2000-11-28 | 2004-03-23 | Matsushita Electric Industrial Co., Ltd. | Method for manufacturing semiconductor and method for manufacturing semiconductor device |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000091620A (en) * | 1998-09-09 | 2000-03-31 | Fujitsu Ltd | Hg-BASED II-VI COMPOUND SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF |
| CN102420173A (en) * | 2011-06-07 | 2012-04-18 | 上海华力微电子有限公司 | Surface treatment method for improving copper interconnection reliability |
| CN102437069A (en) * | 2011-11-30 | 2012-05-02 | 上海华力微电子有限公司 | Method and device for monitoring pretreatment in low-dielectric-constant barrier layer process |
| CN106158727A (en) * | 2015-03-30 | 2016-11-23 | 中芯国际集成电路制造(上海)有限公司 | Copper metallization technology |
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