JP2013080779A - Semiconductor device manufacturing method and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method which buries a conductive material tightly inside a fine groove to obtain wiring excellent in conductivity, and provide the semiconductor device.SOLUTION: In formation of an intermediate layer, the intermediate layer can be deposited on an internal surface of a groove 12 with a uniform thickness by generating a magnetic field by a second coil 46 and a third coil 61 so as to cause magnetic lines of force M1 to pass between a target 53 and a base substrate 11.

Description

  The present invention relates to a semiconductor device manufacturing method and a semiconductor device, and more particularly to a technique for forming fine wiring with high accuracy.

  Conventionally, Al (aluminum) or an Al alloy has been used as a fine wiring material such as a semiconductor element formed on a substrate. However, since Al has a low melting point and poor migration resistance, it has been difficult to cope with high integration and high speed of semiconductor elements.

  For this reason, Cu (copper) has recently been used as a wiring material. Cu has a higher melting point than Al and has a lower electrical resistivity, and is therefore a promising LSI wiring material. However, when Cu is used as a wiring material, there has been a problem that microfabrication is difficult. For example, in Patent Document 1, a groove is formed in an insulating layer, Cu is embedded in the groove, and then Cu is removed from the groove, thereby forming a Cu wiring in a fine groove. A method has been proposed.

Japanese Examined Patent Publication No. 6-103681

However, the invention described in Patent Document 1 has a problem that it is difficult to embed Cu without gaps in the groove.
That is, when Cu is laminated inside the groove by sputtering, Cu is not deposited up to the inside of the fine groove, and Cu is deposited only in the vicinity of the opening end of the groove while the inside of the groove is hollow.
In addition, when the inside of the groove is filled with molten Cu by the reflow method, the wettability with the molten Cu is poor with respect to the barrier metal layer previously formed on the inner wall surface of the groove, and a cavity is generated inside the groove. There existed a subject that Cu solidified in the state.
When a cavity is formed in the Cu wiring formed inside the groove in this way, the resistance value of the Cu wiring becomes high and there is a risk of disconnection.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a semiconductor device manufacturing method and a semiconductor device capable of obtaining a wiring having excellent conductivity by embedding a conductive material in a fine groove without gaps. provide.

In order to solve the above problems, the present invention provides the following method for manufacturing a semiconductor device and semiconductor device.
That is, a method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device comprising at least a groove forming step for forming a groove in a substrate and an intermediate layer forming step for forming an intermediate layer covering at least the inner wall surface of the groove. A method,
In the intermediate layer forming step, a target containing Cu as a main component and added with Mn is disposed opposite to the substrate, and a sputtering gas is introduced into a process chamber in which the substrate and the target are arranged to sputter the target. And a step of forming a magnetic field so that magnetic lines of force are generated in a direction connecting the base and the target, and forming an intermediate layer containing Cu as a main component and containing a Mn compound on the inner wall surface of the groove. To do.

    In the subsequent step of the intermediate layer forming step, the intermediate layer is heated to form a barrier layer containing a Mn compound on the inner wall surface of the groove and a base layer mainly composed of Cu on the surface of the barrier layer. The method further includes a step.

    The method further includes an embedding step of embedding a conductive material in an inner region of the base layer.

    The Mn compound is Mn oxide or Mn nitride.

    The semiconductor device of the present invention is manufactured by the method for manufacturing a semiconductor device described in the above items.

According to the method of manufacturing a semiconductor device and the semiconductor device of the present invention, in the intermediate layer forming step, a magnetic field is generated so that the magnetic lines of force pass between the target and the base, so that the intermediate wall surface has a uniform thickness on the inner wall surface of the groove. Layers can be deposited. And the constituent material of an intermediate | middle layer enters equally into a groove part, and can form the intermediate | middle layer of uniform thickness on the inner wall face of a groove part.
As a result, it is possible to embed a conductive material densely in the groove without a gap, and it is possible to obtain a semiconductor device having a wiring having excellent conductivity in which a conductive material is buried in a fine groove without a gap. become.

It is a principal part expanded sectional view which shows an example of the semiconductor device of this invention. It is the principal part expanded sectional view which showed the manufacturing method of the semiconductor device of this invention in steps. It is the principal part expanded sectional view which showed the manufacturing method of the semiconductor device of this invention in steps. It is a schematic sectional drawing which shows an example of the film-forming apparatus (sputtering apparatus). It is explanatory drawing which shows the effect | action of the film-forming apparatus. It is a schematic sectional drawing which shows an example of a heating apparatus.

    A semiconductor device manufacturing method and a semiconductor device according to the present invention will be described below with reference to the drawings. Note that this embodiment is described by way of example in order to better understand the gist of the invention, and does not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for convenience, and the dimensional ratio of each component is the same as the actual one. Not necessarily.

(Semiconductor device)
FIG. 1 is an enlarged sectional view of an essential part showing an example of a semiconductor device of the present invention.
The semiconductor device 10 includes a base body 11. The base 11 is composed of an insulating substrate such as a glass substrate or a resin substrate. For example, a semiconductor element or the like may be formed on a part of the base body 11.

  A groove portion (trench) 12 is formed on one surface 11 a of the base 11. The groove portion 12 is formed of, for example, a fine groove having a narrow width and deep (high aspect ratio) dug down in the thickness direction of the base body 11 from the one surface 11a of the base body 11. The width W of the bottom of the groove 12 is formed to be, for example, about 20 nm to 50 nm. Further, the depth D of the groove 12 is formed to be, for example, about 80 nm to 200 nm. For example, a conductor constituting the circuit wiring of the semiconductor element is formed in the inner region of the groove 12.

  In the groove portion 12, a barrier layer (barrier metal) 13 is formed so as to cover the inner wall surface 12a. The barrier layer 13 is made of, for example, Mn oxide or Mn nitride. Such a barrier layer 13 is formed by thermally diffusing Mn (manganese) contained in the intermediate layer formed in the groove 12 toward the inner wall surface 12a and reacting with oxygen or nitrogen. A method for forming such a barrier layer 13 will be described in detail later. The barrier layer 13 is formed so that the thickness t1 is, for example, about 1 nm to 3 nm.

  Further, a base layer 14 is formed so as to cover the barrier layer 13. The base 14 is made of, for example, a material containing Cu (copper) as a main component and Mn (manganese). The underlayer 14 is formed so that the thickness t2 is, for example, about 3 nm to 8 nm.

  A conductor 15 made of a conductive material is formed in an inner region of the base layer 14 in the groove 12. The conductor 15 is made of Cu. The conductor 15 is formed by depositing Cu inside the underlayer 14 by, for example, sputtering or plating growth. Alternatively, it is also preferable to form the conductor 15 filling the groove 12 by forming a seed layer inside the base layer 14 and melting (reflowing) the seed layer. The conductor 15 is, for example, a circuit wiring of a semiconductor element formed on the base 11.

(Method for manufacturing semiconductor device)
FIG. 2 and FIG. 3 are enlarged cross-sectional views of the relevant part showing the manufacturing method of the semiconductor device of the present invention step by step.
When manufacturing the semiconductor device of the present invention, first, the base 11 is prepared (see FIG. 2A). As the base 11, an insulating substrate or a semiconductor substrate is used. Examples of the insulating substrate include a glass substrate and a resin substrate. Moreover, as a semiconductor substrate, a silicon wafer, a SiC wafer, etc. are mentioned, for example. Furthermore, it is preferable to use a substrate 11 in which an insulating layer such as an oxide film is formed on one surface of a semiconductor substrate. For example, a semiconductor element (not shown) is formed on the base 11 in advance.

    Next, a groove portion 12 having a predetermined depth is formed on one surface 11a of the base 11 (see FIG. 2B: groove portion forming step). The groove portion 12 is formed, for example, so as to have a pattern that represents a circuit wiring of a semiconductor element. As a method for forming the groove 12 on the one surface 11a of the base 11, for example, etching by photolithography or processing by laser light can be used.

    Next, an intermediate layer 16 having a predetermined thickness is formed on one surface 11a of the base 11 including the inner wall surface 12a of the groove 12 (see FIG. 2C: intermediate layer forming step). The intermediate layer 16 is made of, for example, a main component of Cu and a predetermined amount (for example, 0.2 to 5 atomic%) of Mn.

    FIG. 4 is a schematic cross-sectional view showing a film forming apparatus (sputtering apparatus) used in the intermediate layer forming step. The film forming apparatus 51 is of a DC magnetron sputtering type and includes a process chamber 52 capable of forming a vacuum atmosphere. A cathode unit C is attached to the ceiling of the process chamber 52. In this embodiment, the process chamber 52 will be described below with the ceiling side being “upper” and the bottom side being “lower”.

    The cathode unit C includes a target 53, and the target 53 is attached to a holder 55. The target 53 is an alloy target in which a component constituting the intermediate layer 16, for example, Cu is a main component and Mn is added in a predetermined amount (for example, 0.2 to 5 atomic%), and when the target 53 is magnetron sputtered, Sputtered particles made of an alloy material containing Cu as a main component and added with Mn are emitted.

    Further, the cathode unit C includes first magnetic field generating means 54 that generates a tunnel-like magnetic field in front of the sputtering surface (lower surface) 53a of the target 3. The target 53 is formed in a predetermined shape (for example, a circular shape in plan view) by a known method so that the area of the sputter surface 53a is larger than the surface area of the substrate 11 corresponding to the shape of the substrate 11 to be processed. The target 53 is electrically connected to a DC power source (sputtering power source) 59 having a known structure so that a predetermined negative potential is applied.

    The first magnetic field generating means 54 is arranged on the side (upper side) facing away from the sputtering surface 53a, and the polarity of the target 53 side is alternately changed to the lower surface of the yoke 54a and the yoke 54a arranged in parallel to the target 53. It is comprised from the arrange | positioned magnet 54b, 54c.

    The shape and the number of the magnets 54b and 54c are appropriately selected depending on the magnetic field to be formed in front of the target 53 from the viewpoint of the stability of discharge and the improvement of the use efficiency of the target. The first magnetic field generating means 54 may be configured to reciprocate or rotate on the back side of the target 53.

    A stage 40 is disposed at the bottom of the process chamber 52 so as to face the target 53 so that the substrate 11 can be positioned and held. A gas pipe 41 for introducing a sputtering gas is connected to the side wall of the process chamber 52, and the other end communicates with a gas source via a mass flow controller (not shown). Further, the process chamber 52 is connected to an exhaust pipe 42a that communicates with a vacuum exhaust means 42 such as a turbo molecular pump or a rotary pump.

The second magnetic field generating means 43 and the third magnetic field generating means 48 for controlling the incident directions of metal ions, rare gas (such as argon) ions and electrons are installed around the process chamber 52.
The second magnetic field generating means 53 and the third magnetic field generating means 58 are arranged on the outer wall of the process chamber 52 around the vertical axis CL connecting the centers of the target 53 and the substrate 11 and at a predetermined interval in the vertical direction. It is possible to energize the second coil 16 and the third coil 61 and the second coil 46 and the third coil 61 formed by winding the conductive wires 45 and 60 on the ring-shaped coil supports 44 and 49 provided in the first and second coils, respectively. And power supply devices 47 and 62.

    Here, the number of coils, the diameter and the number of turns of the conducting wire 45 are, for example, the size of the target 53, the distance between the target 53 and the base 11, the rated current of the power supply devices 47 and 62, and the strength of the magnetic field to be generated. It is set appropriately according to (Gauss).

    The power supply devices 47 and 62 have a known structure provided with a control circuit (not shown) that can arbitrarily change the current and the direction of the current to the second coil 46 and the third coil 61. In the present invention, in order to control the incident directions of metal ions, argon ions, and electrons, a negative current can be applied to the second coil 46 so that a downward vertical magnetic field is generated. On the other hand, a positive current can be applied to the third coil 61 so as to generate an upward vertical magnetic field.

    FIG. 5 is an explanatory diagram showing lines of magnetic force M formed by the second magnetic field generating means 43 and the third magnetic field generating means 48. Here, although the magnetic lines of force M are illustrated using arrows, the arrows are for convenience of explanation and do not limit the direction of the magnetic field. Both N → S and S → N directions are included.

    FIG. 5 shows the lines of magnetic force M <b> 1 when a negative current is applied to both the second coil 46 and the third coil 61. By applying a negative current to the second coil 46 and the third coil 61, a magnetic field is generated so that the magnetic lines of force M 1 pass between the target 53 and the base body 11.

While evacuating the inside of the process chamber 52 of the film forming apparatus 51 having such a configuration by the evacuation means 42, a sputtering gas and a reaction gas containing nitrogen or oxygen in the chemical structure are introduced from the gas pipe 41 (for example, reaction When the gas is oxygen, the flow rate is 0.1 sccm or more and 5 sccm or less, and a film-forming atmosphere lower than atmospheric pressure (for example, the total pressure is 10 ⁻⁴ Pa or more and 10 ⁻¹ Pa or less) is formed inside the process chamber 52.

Then, when the process chamber 52 is placed at the ground potential and a negative voltage is applied to the target 53 while maintaining the film forming atmosphere inside the process chamber 52, the target 53 is magnetron sputtered. When the target 53 is magnetron sputtered, sputtered particles made of an alloy material containing Cu as a main component and added with Mn are emitted.
At this time, by applying a negative current to both the second coil 46 and the third coil 61, a magnetic field is generated so that a magnetic force line M1 is generated in a direction connecting the base 11 and the target 53.

  The released sputtered particles and the reactive gas are incident on one surface 11 a where the groove portion 12 is formed on the substrate 11, and a thin film containing the reactive gas in the alloy material grows on the surface and the inner wall surface of the groove portion 12. At this time, a high frequency voltage (including 0 V) is applied to the stage 40, and an amount of plasma corresponding to the magnitude of the high frequency voltage is incident on the surface 11a on which the groove portion 12 of the substrate 11 is formed. The thin film that grows is etched.

  The negative voltage and the high-frequency voltage indicate that the film thickness growth rate (sputtering rate) when the thin film is not etched is the film thickness decrease rate when the thin film is assumed to be etched without growth. As shown in FIG. 2C, the intermediate layer 16 grows on the inner wall surface such as the side wall and the bottom surface of the groove portion 12 and the one surface 11 a of the base material 11. (Intermediate layer forming step).

  When the intermediate layer 16 is formed, a magnetic field is generated by the second coil 46 and the third coil 61 so that the magnetic lines of force M1 pass between the target 53 and the base 11, so that the inner wall surface of the groove 12 is uniform. The intermediate layer 16 can be formed with a thickness.

  That is, when the intermediate layer is formed without applying the magnetic force line M1 between the target 53 and the substrate 11, the components of the intermediate layer are excessively deposited near the opening end of the groove 12, and the opening end of the groove 12 is blocked. It may be narrowed. In this state, if a conductor is embedded inside the groove portion in a later step, a cavity is generated inside the groove portion, causing disconnection or poor conduction.

  However, when the intermediate layer 16 is formed, a magnetic field is generated so that the magnetic lines of force M1 pass between the target 53 and the base body 11, so that the constituent material of the intermediate layer 16 enters evenly into the groove 12, and the inner wall surface of the groove 12 The intermediate layer 16 having a uniform thickness can be formed.

  Next, the intermediate layer 16 formed on the substrate 11 is heated to form a barrier layer 13 containing a Mn compound on the inner wall surface of the groove 12 and a base layer 14 containing Cu as a main component on the surface of the barrier layer 13. It forms (refer Fig.3 (a): heating process).

FIG. 6 is a schematic sectional view showing an example of a heating device for heating the substrate.
The heating device 65 includes a heating chamber 66 and an evacuation system 67 connected to the heating chamber 66. The vacuum exhaust system 67 is activated to form a vacuum atmosphere in the heating chamber 66, and the base material 11 on which the intermediate layer 16 is formed is carried into the heating chamber 36 while maintaining the vacuum atmosphere.

  A heater 68 is disposed inside the heating chamber 66. In order to prevent the oxidation of the intermediate layer 16 by energizing the heater 68, the temperature of the substrate 11 is raised during the intermediate layer forming process while maintaining a vacuum atmosphere. The intermediate layer 16 is annealed by heating at a temperature higher than the temperature to be heated (for example, at 350 ° C. for 2 hours).

As shown in the enlarged view at the bottom of FIG. 3a, Mn contained in the intermediate layer 16 has a high diffusion rate in Cu, and when the intermediate layer 16 is heated during annealing, Mn contained in the intermediate layer 16 diffuses. And reaches the inner wall surface of the groove 12.
Mn has a higher reactivity with respect to nitrogen and oxygen than Cu, and the reactivity is further enhanced by adding the above-described reaction gas to the intermediate layer 16.

Here, for example, when the base material 11 is made of a nitride such as SiN or an oxide such as SiO ₂ , Mn is an interface of the base material 11 and an oxide or nitride contained in the base material 11. Reacts with the precipitation of manganese nitride and manganese oxide.
At this time, when the reaction gas contains nitrogen, manganese nitride, which is a reaction product of nitrogen and Mn of the reaction gas, precipitates at each interface, and when the reaction gas contains oxygen, it is a reaction product of oxygen and Mn of the reaction gas. Some manganese oxide is deposited at each interface.

  The barrier layer 13 made of manganese nitride or manganese oxide is formed on the inner wall surface 12a of the groove 12 and the one surface 11a of the substrate 11 by such thermal diffusion of Mn, oxidation reaction, and nitridation reaction. Further, Cu, Mn, and a part of the reactive gas that are the main components of the intermediate layer 16 remain on the surface of the barrier layer 13, and the remaining intermediate layer 16 becomes the underlayer 14.

  The underlayer 14 has Cu as a main component like the intermediate layer 16, and Cu easily diffuses into silicon oxide or silicon, but manganese oxide and manganese nitride have a property of shielding the diffusion of Cu, so Is shielded by the barrier layer 13 and does not enter the substrate 11.

Next, a conductive material is embedded in the inner region of the base layer (see FIG. 3B: embedding step).
For example, when the conductive material M made of Cu is embedded in the inner region of the base layer 14 formed in the groove 12 of the base material 11, a sputtering method can be used.
When the conductive material is embedded by sputtering, the conductive material made of Cu is deposited on the one surface 11a side of the base 11 including the inner region of the underlayer 14 using the film forming apparatus shown in FIG.

  Thereafter, the barrier layer 13, the base layer 14, and the conductive material M laminated on the one surface 11a of the base 11 excluding the groove 12 are removed (see FIG. 3C). As a result, a conductor 15 that fills the groove 12, that is, a circuit wiring is formed for each groove 12.

DESCRIPTION OF SYMBOLS 10 Semiconductor device, 11 base | substrate, 12 groove part (trench), 13 barrier layer, 14 base layer, 15 conductor (circuit wiring), 16 intermediate | middle layer.

Claims (5)

An intermediate layer forming step of forming an intermediate layer covering an inner wall surface of the base groove portion, and a method of manufacturing a semiconductor device comprising at least
In the intermediate layer forming step, a target containing Cu as a main component and added with Mn is disposed opposite to the substrate, and a sputtering gas is introduced into a process chamber in which the substrate and the target are arranged to sputter the target. And a step of forming a magnetic field so that magnetic lines of force are generated in a direction connecting the base and the target, and forming an intermediate layer containing Cu as a main component and containing a Mn compound on the inner wall surface of the groove. A method for manufacturing a semiconductor device.   In the subsequent step of the intermediate layer forming step, the intermediate layer is heated to form a barrier layer containing a Mn compound on the inner wall surface of the groove and a base layer mainly composed of Cu on the surface of the barrier layer. The method of manufacturing a semiconductor device according to claim 1, further comprising a step.   3. The method of manufacturing a semiconductor device according to claim 2, further comprising an embedding step of embedding a conductive material in an inner region of the base layer.   4. The method of manufacturing a semiconductor device according to claim 1, wherein the Mn compound is Mn oxide or Mn nitride. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 1.

Images