KR101527374B1 - Remote radical cleaning and dry cleaning apparatus and method of using it - Google Patents

Abstract

Disclosed are a remote radical cleaning and a dry cleaning apparatus and a method of using the same. The present invention uses a tandem type source as remote plasma where transformer coupling plasma (TCP) using a ferrite core and an inductive coupling plasma (ICP) source are connected in series. + DC power is applied to a path which connects the remote plasma and a chamber, so ion energy is controlled by controlling the amount of ions passing through with a radical and applying - DC power to a wafer chuck as a pulse, to transmit energy to the bottom of a deep contact hole without the loss of a critical value due to the collision of ions, and increase reactivity. The present invention can effectively remove polymer residues, a natural oxidation layer, and a silicon damage layer, and can perform in-situ passivation on a Si surface without an additional thermal process.

Description

Technical Field [0001] The present invention relates to a remote radical dry cleaning apparatus and a cleaning method using the same,

The present invention relates to a remote radical dry cleaning apparatus and a cleaning method using the remote radical dry cleaning apparatus, and more particularly, to a remote radical dry cleaning apparatus for removing a polymer, a natural oxide film, a damaged silicon film remaining on the bottom of a contact hole after semiconductor etching, .

Generally, in a process of forming wiring in a semiconductor memory fabrication process, a contact hole is formed and then polysilicon is filled in the contact hole to form a wiring.

That is, a contact hole is formed in the semiconductor substrate. Subsequently, the substrate is subjected to ashing and then wet-cleaned.

Once the wet cleaning is complete, the exposed thin film is etched through the contact hole to minimize contact resistance.

Next, the substrate is pre-cleaned to remove the native oxide film formed in the contact hole, and then the polysilicon is filled in the contact hole to form a wiring.

As the semiconductor device is miniaturized, the aspect ratio of the contact hole is increased. As a result, wet cleaning can not remove the polymer residues, natural oxide film, and silicon damage layer remaining on the bottom after the contact hole etching.

In order to remove the natural oxide film remaining on the bottom of the contact hole after etching, equipment using vapor or remote plasma at high temperature is used, but the critical dimension (CD) of the contact is increased There is a problem that particles are generated due to a lack of plasma decomposition efficiency.

Also, in both methods, a deep contact with a large aspect ratio has a problem in that it is ineffective due to lack of reactivity at the bottom of the contact hole.

SUMMARY OF THE INVENTION The present invention has been conceived to overcome the problems of the prior art described above, and it is an object of the present invention to provide a tandem type source in which a transformer coupled plasma (TCP) using a ferrite core and an inductively coupled plasma source The present invention provides a remote radical dry cleaning apparatus that removes residual polymer, natural oxide film, and damaged silicon film on the bottom of a contact hole after semiconductor etching by using plasma as a gas to improve gas decomposition efficiency.

In addition, DC power is applied to the passage connecting the remote plasma and the chamber to control the amount of ions passing through the radical, and DC power is applied to the wafer chuck in a pulse By controlling the energy of the ions, energy is transferred to the bottom of the deep contact hole without loss of the critical number (CD loss) due to ion collision, thereby increasing the reactivity and effectively preventing the polymer residue, natural oxide film and silicon damage layer The present invention provides a cleaning method using a remote-type dry-cleaning device capable of performing passivation on a silicon (Si) surface in-situ without additional heat treatment.

SUMMARY OF THE INVENTION [0008]

Two tandem units are connected in series to the outside of the reactor. When the antenna is wound around the ferrite core, the electric field is induced in a linear direction. A tandem plasma source generating unit for generating a rotation direction of the tandem plasma source;

A process chamber coupled to the tandem plasma source generator through which a semiconductor wafer is fixed;

A power supply unit mounted on a passage connecting the tandem plasma source generating unit and the process chamber and adjusting the amount of ions passing through the plasma by applying DC power;

A CCP generator connected to an upper portion of the process chamber to apply CCP to generate additional energy to radicals and ions generated in the tandem plasma source generator and into the process chamber to increase reactivity;

A DC pulse power supply unit for accelerating ions by applying DC power to the chuck to increase the reactivity by supplying energy to the bottom of the contact hole;

The present invention can be achieved by a remote-type dry-cleaning apparatus.

The tandem plasma source generating unit includes a reactor having upper and lower openings and a passageway formed therein, and a TCP generating unit for generating TCP by winding an antenna around the ferrite core formed on the outer periphery of the reactor, And an ICP generator is formed between the TCP generators.

And a generator for supplying power to an antenna connected to the ferrite core and the chamber of the reactor.

And a secondary gas injection unit is formed on one side of the process chamber to discharge the CCP.

The process chamber includes a cover to which a tandem plasma source generating unit is coupled and a body having an open upper portion to which the cover is coupled. An electrode unit is formed inside the cover, the electrode unit is connected to the tandem plasma source generating unit, And the power supply unit is connected to one side to apply DC power.

The electrode unit is inserted into a groove formed in the inner periphery of the lid, the lower portion is supported by an independent block formed at the step of the groove, the lower portion is extended downward to form a bridge on both sides, And a shower head.

According to another aspect of the present invention, there is provided a cleaning method using a remote radical dry cleaning apparatus, comprising: a first step of loading a semiconductor wafer onto a chuck; A second step of generating radicals and ions in the tandem plasma source generating unit; The radical is diffused into the process chamber, and the amount of ions is determined by + DC power; 4) secondary activation of radicals and ions with CCP in the process chamber; The radicals are diffused to the bottom of the contact hole and the ions are accelerated to the bottom of the contact hole with DC power; Six steps of soft etching to remove polymeric residues, native oxide, and damaged silicon film; And a step 7 of passivating the surface of the silicon (Si) layer in-situ by a cleaning method using a remote-type dry-cleaning apparatus.

According to the present invention, first, a tandem plasma source structure in which TCP and ICP are connected in series by using a ferrite core increases the gas decomposition efficiency to secure the F radical, and in the process of securing the H radical, Thereby suppressing the generation.

Secondly, in order to secure the H radical, in addition to the direct decomposition of the ammonium gas, it induces hydrogen and oxygen (O) reaction such as methane (CH4) including H in the plasma to suppress polymer formation (NHx) do.

Third, the DC power is used to control the amount of ions flowing into the process chamber independently of the radicals.

Fourth, the radicals and ions introduced into the process chamber are further activated by the CCP applied to the upper portion of the process chamber.

Fifth, the ions in the process chamber are accelerated by the DC pulse power applied to the bottom of the process chamber to supply energy to the bottom of the contact hole.

Sixth, passivation of the silicon surface at the bottom of the contact hole through plasma treatment of H radical prevents natural oxide film regeneration and eliminates the subsequent heat treatment process, thus realizing process simplification.

1 shows a remote radical dry cleaning apparatus according to the present invention,
FIG. 2 is a conceptual diagram of a 'tandem plasma source generating unit' in a remote radical dry cleaning apparatus according to the present invention;
FIG. 3 is a flowchart illustrating a cleaning method using a remote radical dry cleaning apparatus according to the present invention.
Figure 4 illustrates a cleaning reaction using a remote radical dry cleaning device in accordance with the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a conceptual diagram of a 'tandem plasma source generating unit' in a remote radical dry cleaning apparatus according to the present invention, and FIG. 3 is a schematic diagram of a tandem plasma source generating unit according to the present invention FIG. 4 is a view showing a cleaning reaction using a remote radical dry cleaning apparatus according to the present invention. FIG. 4 is a flowchart illustrating a cleaning method using a remote radical dry cleaning apparatus according to an embodiment of the present invention.

TCP, which is mentioned in the following description, is defined as a transformer-coupled plasma, ICP is defined as an inductively coupled plasma, and CCP is defined as a capacitively coupled plasma.

1 to 2, a remote radical dry cleaning apparatus according to the present invention includes a tandem plasma source generating unit 2, a process chamber 4, a power supply unit 5, a CCP generating unit 6, , And a DC pulse power supply unit (8).

The tandem plasma source generator 2 has two tandem units with two different plasma combinations, and two or more tandems are connected in series to the outside of the reactor 22.

2, power is supplied to the antenna connected to the ferrite core 242 to generate TCP, the electric field is induced in a linear direction, power is supplied to the antenna 25 formed around the reactor 22, The induction electric field is formed in the direction of rotation around the reactor 22.

The ferrite core 242 may have a U-shape or a quadrangle shape depending on the torroid shape or the workability.

The tandem plasma source generating section 2 includes a reactor 22 having upper and lower openings and a passage formed therein and an antenna 25 wound around a ferrite core 242 formed on the outer periphery of the reactor 22, And the ICP generating unit 26 is formed by winding the antenna 25 between the TCP generating unit 24 and the ICP generating unit 26. [

The combination of TCP and ICP, which are the different plasma sources described above, can be one unit (tandem), and the tandem source can be repeated in series.

And the tandem source is installed as a remote plasma.

A generator for supplying power to the ferrite core 242 of the reactor 22 and an antenna 25 connected to the ferrite core 242, that is, the TCP generating unit 24 and the ICP generating unit 26 are provided.

The TCP generating unit 24 and the ICP generating unit 26 are connected to one generator or connected to two independent generators, respectively.

When connected to one generator, the TCP and ICP frequencies are 280 to 420 kHz.

When connected to two independent generators, the TCP frequency is 280 to 420 kHz and the ICP frequency is 13.56 to 60 MHz.

The gas introduced into the reactor 22 includes hydrocarbons such as CF ₄ , SF ₆ , NF ₃ containing F and CH ₄ containing H, NH ₃ and O ₂ .

The introduced gas includes a gas containing F, a gas containing H, and O ₂ in a one-step soft etch (polymer residue, natural oxide film, damaged silicon film removal).

The introduced gas comprises a gas containing H and O ₂ in a two-step passivation.

The soft etch and passivation proceed in-situ.

The process chamber 4 is coupled to the tandem plasma source generating unit 2 through an upper portion thereof and a chuck 43 to which the semiconductor wafer 100 is fixed.

That is, the process chamber 4 includes a lid 41 to which the tandem plasma source generating unit 2 is coupled, and a body 42 having an upper opening to which the lid 41 is coupled.

An electrode unit 7 is formed on the inside of the lid 41. The electrode unit 7 is connected to the tandem plasma source generating unit 2 and the power supply unit 5 is connected to one side of the lid 41, power is applied.

A second gas injection unit 9 is provided at one side of the process chamber 4 to apply CCP to the process chamber 4. The CCP is applied to the upper part of the process chamber 4 so that radicals and ions generated in the plasma source are activated in the process chamber do.

The CCP frequency is 13.56 to 60 MHz.

A separate gas inlet is installed at the site where the CCP is applied, and an inert gas such as He is introduced into the gas inlet.

The electrode unit 7 is inserted into a groove 44 formed in the inner periphery of the lid 41 and is supported by the independent block 46 formed at the step of the groove 44, A bridge 72 is formed on both sides and a showerhead 74 connecting the bridges 72 on both sides is formed.

Preferably, the electrode portion 7 is formed in a disk-like shape or a radial shape, and the outer periphery is bent downward or vertically welded to form the bridge 72.

The shower head 74 is supported by the bridge 72 formed at the edge of the electrode part 7 so as to be arranged parallel to the chuck 43. [

DC power is applied to the lower portion of the chuck 43 on which the semiconductor wafer 100 is loaded to accelerate ions.

The DC power is applied in the form of a pulse.

The temperature of the chuck 43 on which the semiconductor wafer 100 is loaded is 10 to 200 占 폚.

The power supply unit 5 is mounted in a passage between the tandem plasma source generating unit 2 and the process chamber 4 and applies DC power to adjust the amount of ions passing therethrough.

The CCP generator 6 is connected to an upper portion of the process chamber 4 to apply CCP to generate additional energy from the tandem plasma source generator 2 to radicals and ions entering the process chamber to increase reactivity.

The DC pulse power supply unit 8 accelerates ions by applying DC pulse power to the chuck 43 to increase the reactivity by supplying energy to the bottom of the contact holes.

The DC power supply 82 and the chuck 43 are connected to each other to apply DC pulse power.

On the other hand, as shown in Fig. 3, the cleaning method using the remote radical dry cleaning apparatus (A)

A first step (S1) of loading the semiconductor wafer (100) onto a chuck;

A second step S2 of generating radicals and ions in the tandem plasma source generating unit 2;

(S3) in which the radical is diffused into the process chamber 4 and the amount of ions is determined by + DC power;

A fourth step S4 of secondary activation of radicals and ions in the process chamber 4 by CCP;

(S5) in which the radicals are diffused to the bottom of the contact hole and the ions are accelerated to the bottom of the contact hole with DC power;

A sixth step (S6) of removing the polymeric residue, natural oxide film, and damaged silicon film by soft etching;

Step 7 (S7) of passivating the silicon (Si) surface in-situ;

.

The tandem plasma source generating unit 2 connects two or more tandems in series by using two different plasma sources TCP and ICP as one tandem unit.

When the antenna 25 is wound around the ferrite core 242 to generate TCP, the electric field is induced in the linear direction, whereas in the ICP, the induced electric field becomes the rotating direction.

Therefore, in the induction electric field as described above, the movement of the electrons can be combined with a straight line and a rotational motion to increase the decomposition efficiency of gas (for example, perfluorocarbon, etc.) relative to a single plasma source.

On the other hand, the radicals generated in the plasma source are diffused into the process chamber 4, but the repulsion generated between the same charges by the DC power applied to the path connecting the plasma source and the process chamber 4 And the amount of ions passing through the process chamber 4 is determined according to the magnitude of the applied + DC power.

In the case of a direct plasma generated directly in the process chamber 4 as in the conventional plasma source method, there is no method of separately controlling the amounts of radicals and ions. In a method of generating them remotely, Only radicals and ions in the resulting radicals are used.

Therefore, the concept of controlling the amount of radicals and ions separately as intended in the present invention is to prevent the problem that the threshold value of the upper portion of the contact hole increases due to excessive sputtering of ions, It is suitable for soft etch that supplies energy to hole bottom.

Meanwhile, as shown in FIG. 4, the radicals and ions entering the process chamber 4 are supplied with additional energy by CCP (Capacitively Coupled Plasma) applied to the upper part of the chamber to increase the reactivity.

The radical reaches the bottom of the contact hole by diffusion and reacts, and the ions accelerate to the DC power applied to the lower chuck of the semiconductor wafer to reach the bottom of the contact hole to activate the radical reaction.

On the other hand, the primary gas injected into the tandem plasma source generator 2 is selected from the group of NH ₃ and CH ₄ based on NF ₃ , SF ₆ and CF ₄ containing F and containing O ₂ and H.

The F radical formed in NF ₃ , SF ₆ and CF ₄ acts as a etchant for removing the polymer 310, the natural oxide film 320 and the damaged silicon film 330 in the contact hole 200.

H radical formed in NH ₃ and CH ₄ plays a role of regulating the etch rate necessary for soft etch because it forms a reactive HF by reacting with F radical to reduce the corrosive liquid, After the natural oxide film 320 and the damaged silicon film 330 are removed, passivation of the silicon surface is performed to prevent further natural oxide film formation.

On the other hand, the oxygen radical (O radical) formed in O ₂ contributes to the removal of the polymer remaining in the contact hole, and secondly, it reacts with CF ₄ and CH ₄ in the plasma to suppress the generation of polymer such as CF x and CH x, Radicals, H radicals (CF ₄ + O → 4F + CO, CH ₄ + O → 4H + CO).

Meanwhile, the CCP applied to the upper end of the process chamber 4 generates a plasma in the ion state with the radicals generated in the tandem plasma source generating unit 2 and diffused into the process chamber 4, .

An inert gas such as He, which has a small sputtering effect, may be injected into the secondary gas inlet to control the ion effect.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention, It is obvious that the claims fall within the scope of the claims.

2: tandem plasma source generating unit 4: process chamber
5: Power supply unit 6: CCP generating unit
7: electrode part 8: DC pulse power supply part
22: Reactor 24: TCP generator
25: antenna 26: ICP generator
41: lid 42; body
43: chuck 74: shower head
100: semiconductor wafer

Claims (14)

Two tandem units are connected in series to the outside of the reactor. When the antenna is wound around the ferrite core, the electric field is induced in a linear direction. A tandem plasma source generating unit for generating a rotation direction of the tandem plasma source;
A process chamber coupled to the tandem plasma source generator through which a semiconductor wafer is fixed;
A power supply unit mounted on a passage connecting the tandem plasma source generating unit and the process chamber and adjusting the amount of ions passing through the plasma by applying DC power;
A CCP generator connected to an upper portion of the process chamber to apply CCP to generate additional energy to radicals and ions generated in the tandem plasma source generator and into the process chamber to increase reactivity;
And a DC pulse power supply unit for accelerating the ions by applying DC power to the chuck to increase the reactivity by supplying energy to the bottom of the contact hole,
The tandem plasma source generator
And a TCP generating unit for generating TCP by winding an antenna around the ferrite core formed on the outer periphery of the reactor is formed at each of the upper and lower sides of the reactor, Generating portion is formed,
The process chamber
A tandem plasma source generating unit, and a body having an upper opening to which the cover is coupled,
The electrode unit is connected to the tandem plasma source generating unit, and the power supply unit is connected to one side of the electrode unit to apply DC power.
The electrode portion
A lower portion of which is supported by an independent block formed at a step of the groove, a lower portion of which is extended downward to form a bridge on both sides of the lower portion, and a shower head Is formed on the outer surface of the outer casing
delete The method according to claim 1,
And a generator for supplying power to an antenna connected to the ferrite core and the chamber of the reactor. The method according to claim 1,
And a secondary gas injection unit is formed on one side of the process chamber to discharge CCP. delete The method according to claim 1,
Wherein the combination of TCP and ICP, which are different plasma sources, is one unit (tandem), and the tandem source repeats in series. The method according to claim 6,
Wherein the tandem source is installed with a remote plasma. The method according to claim 1,
Wherein the TCP generating unit and the ICP generating unit are connected to one generator or connected to two independent generators, respectively. 9. The method of claim 8,
Wherein the TCP and ICP frequencies are 280 to 420 kHz when connected to one generator. 9. The method of claim 8,
Wherein the TCP frequency is 280 to 420 kHz and the ICP frequency is 13.56 to 60 MHz when connected to two independent generators. The method according to claim 1,
Characterized in that the gas introduced into the reactor comprises hydrocarbon radicals such as CF ₄ , SF ₆ , NF ₃ containing F and CH ₄ containing H, NH ₃ and O ₂ , Dry cleaning device. A cleaning method using the remote radical dry cleaning apparatus according to claim 1,
Loading a semiconductor wafer onto a chuck;
A second step of generating radicals and ions in the tandem plasma source generating unit;
The radical is diffused into the process chamber, and the amount of ions is determined by + DC power;
4) secondary activation of radicals and ions with CCP in the process chamber;
The radicals are diffused to the bottom of the contact hole and the ions are accelerated to the bottom of the contact hole with DC power;
Six steps of soft etching to remove polymeric residues, native oxide, and damaged silicon film;
Passivation of the silicon (Si) surface in-situ;
The method of claim 1, wherein the cleaning is performed by using a remote radical dry cleaning apparatus. 13. The method of claim 12,
The third step
Wherein the CCP frequency is 13.56 to 60 MHz, and an inert gas is injected into a site to which the CCP is applied. 13. The method of claim 12,
In the first step,
DC power is applied to the lower part of the chuck on which the semiconductor wafer is loaded to accelerate ions,
The DC power is applied in a pulse form,
Wherein the temperature of the chuck on which the semiconductor wafer is loaded is in the range of 10 to 200 ° C.

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