JP3208931B2 - Plasma processing apparatus and plasma processing method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a plasma etching process, a plasma CVD (chemical vapor deposition) process,
The present invention relates to a plasma processing apparatus capable of performing plasma processing such as plasm-massaging processing and a plasma processing method using the same.

[0002]

[Prior art]

For example, in a semiconductor integrated circuit device, a structure is adopted in which an upper wiring is electrically contacted with a lower wiring through a contact hole formed in an interlayer insulating layer of the multilayer wiring structure. In this case, the contact through-hole has been continually miniaturized from the high-density miniaturization of the integrated circuit.
The upper layer wiring, or a conductive material for connecting the upper layer wiring to the lower layer wiring can be satisfactorily filled, and the cross section is formed vertically without being barrel-shaped so that it can be miniaturized. Is desired.

[0004] Anisotropic etching is applied to the drilling of the contact through hole, etc. In this anisotropic etching, charged particles (ions) are generated to give directionality by applying a bias. Reactive ion etching (RIE) is used.

As this RIE, there is a magnetron parallel plate type RIE apparatus which performs a high frequency discharge in a magnetic field. In this magnetron parallel plate type RIE apparatus, plasma is formed by high-frequency discharge, high-frequency power is applied to a mounting table on which an object to be processed is arranged, that is, a cathode, and accelerated by an electric field of an ion sheath generated thereon. The ions are made to collide with the object. Then, the ion species colliding with the object loses energy and emits secondary electrons. Since the secondary electrons have negative charges, they are accelerated in the opposite direction to the ions. The secondary electrons undergo an electric field E × magnetic flux density B drift movement under the influence of the magnetic field, and thus cause a cycloidal movement, which scans the entire surface of the object to be processed, and thereby the collision probability between the electrons and the gas species. And a high-density plasma is generated.

However, in this type of RIE apparatus of the magnetron parallel plate type, the drift of electrons ends at the cathode having a small electric field, that is, at the end surface of the mounting table of the object to be processed. Problem.

[0007] In this case, in the acceleration of ions, energy for generating plasma and energy for accelerating ions are given by applying a high frequency. That is, the acceleration energy of the ions is indirectly determined by the pressure and density of the plasma, and the two cannot be independently selected.

On the other hand, the parallel plate type plasma processing apparatus generates plasma in a space between parallel electrodes. In this case, gas molecules are polymerized by the plasma to generate a polymer.

The generated polymer adheres to, for example, the surface of the semiconductor wafer of the object to be plasma-treated, and this not only causes the deterioration of the characteristics of the plasma processing, for example, the plasma etching processing and the plasma CVD, but also causes the deterioration of the polymer. Is deposited on the entire inner wall surface, which causes so-called particles, which lowers the yield and reliability of a semiconductor device manufactured using this plasma processing apparatus.

[0010] The deposits deposited on the chamber wall adsorb a large amount of impurities and the like on the surface, and during discharge, these impurities are released during the plasma processing operation, thereby deteriorating the stability of the processing.

For example, in the case of an etching apparatus for an oxide film, the etching rate is reduced by deposits adhering to the chamber wall. FIG. 7 shows the result of measuring the etching rate with respect to the number of etched semiconductor wafers when etching is performed by a conventional parallel plate type plasma processing apparatus. The cleaning of the chamber is performed at the times indicated by arrows a and b. Was. As is clear from this, as the wafer processing is repeated, the etching rate decreases, and therefore, as shown by arrows a and b, cleaning is performed on the chamber wall surface every 2000 sheets. is there.

This cleaning is performed by mechanical cleaning in which the chamber is opened to the atmosphere to remove deposits on the chamber wall, and this cleaning requires about 4 hours, and the time and labor loss is small. large.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a uniform plasma can be formed, and further, the control of the plasma density,
Provided is a plasma processing apparatus that can independently control ion acceleration, can use various processing modes with a common apparatus, and can easily perform a cleaning operation without opening to the atmosphere. Things.

[0014]

The apparatus of the present invention adopts a parallel plate type configuration as shown in FIG. 1 as a schematic cross-sectional view of an example thereof, and a mounting table of the object 1 to be processed by the parallel plate type configuration. 2
A low-frequency or high-frequency applying means 4 for applying a low-frequency or high-frequency between the electrode and the opposing electrode 3, ie, the anode; a cylindrical magnetron electrode 11 to which a low-frequency or high-frequency is applied; And a high-density plasma generating means 6 composed of an electromagnet 12 for generating magnetic lines of force along the axial direction of the magnetron electrode 11, and the electrons are permanently cycloidally moved on the magnetron electrode 11. As a result, a frequency synchronized with a cycle in which the cycloidally moving electrons make one round on the inner wall surface of the chamber 5 is applied, and the electrons are cycloidized by the interaction between the bias electric field generated by the magnetron electrode 11 and the magnetic field lines H generated by the electromagnet 12. Rotate in a ring along the inner wall surface of the chamber 5 while moving Configured to generate a high density plasma in the vicinity of.

In the method of the present invention, a first etching step of performing selective etching in an etching mode using the above-described apparatus of the present invention, a mounting table 2 for a workpiece 1 and an opposing electrode 3 facing the same. By applying the deposition step of the protective film in the deposition mode in which the high-density plasma generating means 6 is operated without applying a low frequency or a high frequency between the second step and the second etching step in the etching mode, the deposition is sequentially performed. Perform selective etching on the processing object.

[0016]

According to the apparatus of the present invention, apart from the parallel plate type configuration, high density plasma is generated near the inner wall surface of the chamber 5 by magnetron discharge, which generates high density plasma due to cyclotron motion and rotation of electrons by applying a bias electric field and lines of magnetic force. Since the generating means 6 is provided, the high-density plasma generating means 6 is almost independent of the selection of the ion acceleration energy.
Thus, the plasma energy can be controlled, and the optimum ion acceleration energy and high-density plasma can be generated according to the purpose.

Therefore, the degree of freedom in selecting etching conditions such as selection of a plasma processing speed, for example, an etching speed, and anisotropy of anisotropic etching can be increased.

Further, according to the high-density plasma generating means 6, the electrons are caused to move in a cycloid manner while the chamber 5 is moved.
Since the electrons rotate in a ring shape along the inner wall surface, that is, the electrons are permanently rotated, the stagnation of the electrons is avoided and the plasma is made uniform. The permanent rotation of the electrons is generated by applying a frequency to the magnetron electrode 11 in synchronism with a cycle in which the electrons moving in a cycloid circle the inner wall surface of the chamber 5 once. Therefore, the target plasma processing can be performed accurately and uniformly in combination with the controllability of the plasma density described above.

The combination of the high-density plasma generating means 6 and the parallel-plate type component, ie, the on / off of the high-density plasma generating means 6 and the on / off of the low-frequency or high-frequency applying means 4, Since various discharge modes can be taken, not only RIE (reactive etching) but also RIE using high-density plasma by magnetron discharge (hereinafter referred to as MRIE)
Each etching mode can be set, and each plasma processing in a deposition mode and a cleaning mode can be performed by selecting a process gas to be used.

Since the cleaning can be performed without opening the chamber 5 to the atmosphere, the cleaning can be easily performed. Therefore, by performing cleaning of the chamber 5 each time the processing of each workpiece 1 is completed, the plasma processing is always performed in a clean state. For example, the etching rate is reduced, particles are generated, and the like. Can be avoided, problems such as deterioration of characteristics of each processing of the object 1 to be processed, and thus yield and reliability can be improved, and labor and work time required for this cleaning can be reduced.

According to the method of the present invention, in the selective etching operation, by using the apparatus of the present invention,
By sequentially performing the first etching in the MRIE mode → the deposition in the deposition mode → the second etching mode in the MRIE mode, for example, a so-called just etching of a target depth is performed in the first etching, and thereafter, By the deposition operation, a protective film for etching is applied to the side surface generated by the etching, and then sufficient etching, that is, over-etching can be performed by the second etching. Reliable selective etching can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIG. The apparatus of the present invention has a parallel plate configuration, in which a cathode 7 is arranged on a mounting table 2 of a workpiece 1 in a chamber 5, and a counter electrode 3, that is, an anode is arranged to face the cathode 7.

The mounting table 2 of the object 1 is shielded by a conductor 7 disposed outside the cathode 7 via an insulator 8 such as ceramic.

A low frequency or a high frequency is applied between the mounting plate 2 having the parallel plate structure, ie, between the cathode 7 and the anode 3.
It is supplied from the application means 4, that is, a low frequency or high frequency power supply. The example shown in FIG. 1 is a case where a cathode coupling configuration for supplying a low frequency or a high frequency to the cathode side is employed. In this way, the plasma S ₁ is occurring.

The chamber 5 has, for example, a configuration in which a cylindrical insulator 10 is arranged on the inner periphery of a cylindrical Al container.
The insulator 10 is made of quartz glass, alumina, or the like that does not adversely affect the electrical characteristics of the object 1 when the insulator 10 is sputtered.

Then, high-density plasma generating means 6 is provided. The high-density plasma generating means 6 rotates a ring along the inner wall surface of the chamber 5 while applying a bias electric field and magnetic lines of force near the inner wall surface of the chamber 5 to cause electrons to move in a cycloid manner. A high-density plasma is generated in the vicinity. The rotation of the electrons is generated by applying a low frequency or a high frequency to the magnetron electrode 11 in synchronization with a cycle in which the electrons moving in a cycloid circle the inner wall surface of the chamber 5 once.

The high-density plasma generating means 6 includes a cylindrical magnetron electrode 11 disposed in an insulator 10 of the chamber 5, and a magnetic force line H extending along the axis of the electrode 11.
A coil for generating a magnetic field is wound around the outer periphery of the chamber 5 and is constituted by an electromagnet 12 for generating a magnetic field. A low frequency or a high frequency is applied to the magnetron electrode 11 from a low frequency or a high frequency power supply 13. A self-bias, that is, a potential drop is generated near the wall surface.

Thus, the self bias Vm
As shown schematically in FIG. 2, the electrons move along the inner wall surface of the chamber 1 due to the interaction between the electrons and the lines of magnetic force generated by the electromagnets 12. This cycloidal motion electrons in a ring shape along the inner wall surface, thus rotate endlessly, to form a high density plasma sheath S ₂ near the inner wall surface.

The inside of the chamber 5 is made high vacuum by, for example, a turbo molecular pump 14 and a dry pump 15, and can be operated at, for example, 0.1 Pa to 50 Pa.

[0030] Then, through the gas dispersion plate 16 are a number of holes consisting formed by drilled example quartz plate, the plasma generating section S _1, the dispersion is supplied process gas from the process gas supply port 17.

According to this configuration, the ions are accelerated in the plasma sheath portion S ₃ generated on the processing object 1 on the mounting table 2, and the plasma processing is performed on the processing object 1 by the accelerated ions. You.

According to the apparatus of the present invention, low frequency or high frequency application means, that is, low frequency or high frequency power supply 4 is turned on / off, high density plasma generation means 6 is turned on / off, and MRIE is selected by selecting a process gas. , RIE
Mode, deposition mode, and cleaning mode.

Table 1 shows the relationship between each mode and the operating state of each part, examples of process gas used, and characteristics in each mode.

[0034]

[Table 1]

Next, an example of the method of the present invention using the apparatus of the present invention will be described with reference to the process chart of FIG. The method of the present invention is applied to a case where, for example, selective etching is performed on a wiring layer for forming a wiring pattern by plasma processing. When performing such selective etching,
For example, in order to reliably eliminate the occurrence of a short circuit between the wiring patterns, the etching of the wiring layer is usually over-etching.

In the method of the present invention, even when such over-etching is performed, side etching, ie, lateral etching, occurs. For example, in the case of forming a wiring pattern, there is an inconvenience that the wiring pattern is thinned. Is to avoid.

In this method, the object 1 is subjected to the first MRIE or etching mode
Etching step, the deposition step of the protective film in the deposition mode, and the same MRIE or RI
And a second etching step in the E etching mode.

An embodiment of the method of the present invention will be described. In this embodiment, the etching is performed in the MRIE mode.

Example 1 In this example, the object to be processed 1 is a Si wafer, and an insulating layer 2 made of SiO ₂ having a thickness of 40 nm formed thereon.
In this case, a wiring pattern is formed by etching the wiring layer 27 formed on the substrate 2 into a predetermined pattern. Wiring layer 2
7 is a 5 nm thick Ti layer 23 and a 10 nm thick TiN
Al-Si is formed to a thickness of 1 [mu] m on a base layer composed of the layer 24, and a surface layer 27 having a thickness of 5 nm is formed.

On this wiring layer 27, a photoresist 28
(FIG. 3A).

This wafer, that is, the object 1 is
Is placed on the mounting table 2 in the chamber 5 of the apparatus of the present invention described above, and using the photoresist 28 formed thereon as an etching resist, for example, an etching gas of Cl ₂ is supplied as a process gas, and M indicated by 1
The first etching is performed by the RIE mode operation to form the wiring pattern 29. Etching at this time,
Overetching is avoided and the etching is stopped by so-called just etching in which the wiring layer 27 has just been etched (FIG. 3B).

Subsequently, the operation in the deposition mode based on Table 1 is performed in the same apparatus without changing the process gas to Ar without exposing to the atmosphere. In this way, the insulator 10 on the inner wall of the chamber 1 is sputtered, and the protective film 30 made of an insulating film is deposited on the side surface exposed to the outside of the wiring pattern 29 (FIG. 3C). in this case,
The protective film 30 can be formed by supplying another deposition source gas.

Subsequently, over-etching is performed by the second etching in the same apparatus by the same MRIE mode operation without exposing to the atmosphere (FIG. 3D). After that, the photoresist 28 is removed.

Each MRIE mode in the first embodiment
Table 2 shows each operation condition of the deposition mode and the cleaning mode.

[0045]

[Table 2]

According to the method of the present invention, at the time of over-etching by the second etching, the disadvantage that the wiring pattern is thinned due to the insulating protective film 30 being applied to the side surface of the wiring pattern 29 is avoided. Is done.

Although the deposition step of the protective film 30 is interposed after the first etching step, the first etching step, the deposition step, and the second etching step are all performed continuously in the same apparatus. The operation can be performed extremely efficiently and easily.

After performing such a plasma treatment, the object 1 is taken out, and then, for example, if the cleaning mode operation shown in Table 2 is performed while evacuating, the inner wall surface of the chamber 1 is subjected to magnetron discharge. Deposits such as polymers adhered to the substrate are sputtered and cleaned.

The example shown in FIG. 1 is shown in FIG.
As with the cathode coupling type configuration
In this case, the magnet by the high-density plasma generating means 6
Object 1 independent of high-density plasma generated by
Because the ion energy can be controlled,
For example, for polycrystalline Si films that require energy control
Is performed by the above-described MRIE mode.
It is suitable for. For example, a polycrystalline Si film is used for a semiconductor wafer.
SiO formed on_TwoSmell when formed on a layer
Therefore, when the Si film is selectively etched,
Using HBr as the etching gas, that is, the etching gas,
High frequency, for example, 1 MHz is applied to the mounting table 2, that is, the cathode 7.
By controlling this high frequency bias, for example,
Si film and SiO _TwoControl etch selectivity with layer
SiO2_TwoSelective Si film leaving layer
Etching can be performed.

However, as shown in the configuration diagram of FIG. 5, in the configuration of FIG. 1, the low frequency or high frequency power source 4 is connected to the counter electrode 3, ie, the anode side, and the low frequency or high frequency application is performed. It can also be configured. This configuration has an extremely low ion energy of, for example, about 30 eV to the object 1 and is suitable for use in a deposition mode, particularly as a CVD (chemical vapor deposition) apparatus.

In this configuration, an example in which Si is to be CVD-processed on the object 1 to be processed, for example, a semiconductor wafer, will be described.
In this case, for example, not shown in the table 2 provided the heating means such as a heater, thereby heating the semiconductor wafer of the substrate 1 to 350 ° C. to 500 ° C., monosilane SiH ₄
And supplying He gas. In this case, since low frequency or high frequency bias is applied to the inner wall surface of the counter electrode 3 and the inner wall of the chamber 5, it is possible to prevent the deposit from being attached to these electrodes and the inner wall surface.

As another example of the apparatus of the present invention, a split configuration in which a low frequency or a high frequency is applied to the mounting table 3, ie, the cathode 7 and the counter electrode, as shown in FIG. You can also. This can be applied when etching relatively high ion energy, such as SiO ₂ , to perform highly anisotropic etching. In this case, the process gas can be supplied in a relatively low pressure range of about 10 Pa by supplying CHF ₃ and CO at flow rates of 45 sccm and 175 sccm, respectively.

Then, for example, in the etching of the oxide film, the high-density plasma generating means 6 is turned off to perform split mode etching, and after each etching operation, cleaning is performed, and low frequency or high frequency application to the electrodes 7 and 3 is performed. It can be performed by turning off the high-density plasma generating means 6 as off.

4 to 6, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

According to the apparatus of the present invention, plasma ashing can be performed.

As described above, according to the apparatus of the present invention, various operation modes can be adopted. Thus, in the manufacture of various devices including semiconductor devices, etching, CVD, ashing, and cleaning are arbitrarily combined. Can be performed continuously.

[0057]

As described above, according to the device of the present invention,
Apart from the parallel plate type configuration, by providing a high density plasma generating means 6 by magnetron discharge for generating high density plasma by cyclotron motion and rotation of electrons by applying a bias electric field and lines of magnetic force near the inner wall surface of the chamber 5, By the combination operation of these high-density plasma generating means 6 and the parallel plate type component, not only RIE but also each MRIE etching mode using high-density plasma by magnetron discharge can be taken.
Furthermore, depending on the selection of process gas to be used,
Mode and cleaning mode plasma processing.

Further, since the control of the acceleration energy of ions and the control of the generation of high-density plasma can be performed almost independently, each plasma processing can be performed under optimum conditions according to the intended operation.

The high-density plasma generating means 6 rotates the electrons in a ring along the inner wall surface of the chamber 5 while cycloidally moving the electrons, that is, rotates the electrons infinitely, so that the stagnation of the electrons is avoided and the plasma is made uniform. Is peeled off. Therefore, the target plasma processing can be performed accurately and uniformly in combination with the controllability of the plasma density described above.

According to the apparatus of the present invention, the chamber 5
Can be cleaned without opening to the atmosphere, so that the cleaning can be performed easily and the chamber 5 can be cleaned each time each processing is completed, so that the plasma processing is always performed in a clean state. As described at the beginning, for example, it is possible to avoid inconveniences such as lowering of an etching rate and generation of particles, and problems such as deterioration of characteristics of each processing of the processing target 1 and therefore yield, The reliability can be improved, and the labor and work time involved in the cleaning can be reduced.

According to the method of the present invention, in the selective etching operation, by using the apparatus of the present invention,
Just etching in the first etching step → deposition of the protective film in the deposition mode → over etching in the second etching step, so that selective etching with excellent verticality avoiding side etching can be performed. Can be.

As described above, according to the apparatus and the method of the present invention, many industrial benefits are brought.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of the device of the present invention.

FIG. 2 is a diagram showing the behavior of electrons in a high-density plasma generating means of the apparatus of the present invention.

FIG. 3 is a process chart of one embodiment of the method of the present invention.

FIG. 4 is a configuration diagram of an example of the device of the present invention.

FIG. 5 is a configuration diagram of another example of the device of the present invention.

FIG. 6 is a configuration diagram of still another example of the device of the present invention.

FIG. 7 is a diagram showing a measurement result of an etching rate with respect to a processing number in plasma etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Object to be processed 2 Mounting table 3 Counter electrode (anode) 4 Low frequency or high frequency applying means 5 Chamber 6 High density plasma generating means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 C23C 16/509 C23F 4/00 H01L 21/205

Claims (2)

(57) [Claims] 1. A low-frequency or high-frequency applying means for applying a low-frequency or high-frequency between a mounting table of an object to be processed in the parallel-plate configuration and a counter electrode facing the mounting table. , A cylindrical magnetron to which low or high frequency is applied
A pole and a magnet disposed along the magnetron electrode;
An electromagnet that generates lines of magnetic force along the axis of the electrode
Have a high-density plasma generating means consisting of, the magnetron conductive electrode, electrons are permanently Saikuroi
Cycloid motion
Electrons are synchronized with the cycle of one round of the inner wall of the chamber.
A frequency is applied, and a bias electric field by the magnetron electrode and the electromagnet
A plasma processing apparatus characterized in that electrons are rotated in a ring shape along an inner wall surface of the chamber while performing cycloidal movement by interaction with magnetic lines of force, thereby generating high-density plasma near the inner wall surface of the chamber. 2. A low-frequency or high-frequency applying means for applying a low-frequency or high-frequency between a mounting table of an object to be processed in the parallel-plate configuration and a counter electrode opposed thereto, A cylindrical magnetron to which low or high frequency is applied
A pole and a magnet disposed along the magnetron electrode;
An electromagnet that generates lines of magnetic force along the axis of the electrode
Have a high-density plasma generating means consisting of, the magnetron conductive electrode, electrons are permanently Saikuroi
Cycloid motion
Electrons are synchronized with the cycle of one round of the inner wall of the chamber.
A frequency is applied, and a bias electric field by the magnetron electrode and the electromagnet
Using a plasma processing apparatus that rotates in a ring shape along the inner wall surface of the chamber while causing electrons to move cycloidally due to the interaction with the magnetic field lines due to the magnetic field lines, and generates high-density plasma near the inner wall surface of the chamber, the etching mode A first etching step of performing selective etching by the method described above, and operating the high-density plasma generating means without applying the low frequency or the high frequency between the mounting table of the object to be processed and the opposing electrode facing the mounting table. A plasma processing method, comprising sequentially performing a deposition step of a protective film in a deposition mode and a second etching step in an etching mode.