KR101197019B1 - Gap-fill method using pulsed RF power and gap-fill apparatus for the same - Google Patents

Abstract

The present invention comprises the steps of placing the gap-formed substrate on the substrate support in the chamber; Supplying a non-reactive gas into the chamber and applying a source RF power to generate a plasma in the reaction space above the substrate; Supplying a deposition process gas to the reaction space, converting a bias RF power into pulsed RF and applying it to the substrate stabilizer; Blocking supply of the process gas and application of the bias RF power; It relates to a gap-fill (Gap-fill) method and a gap-fill device therefor including the step of quenching the plasma of the reaction space.

According to the present invention, it is possible to periodically control the energy and partial pressure of ions incident to the opening of the gap by converting and supplying the bias RF power into pulsed RF in the gap fill process. Therefore, the contributions to the deposition and etching and by-products can be smoothly escaped to the outside of the gap periodically without re-deposition, thereby greatly improving the gap fill characteristics.

Gap Fill, HDP CVD, Pulse

Description

Gap-fill method using pulsed RF power and gap-fill apparatus for the same}

1 is a view showing a typical HDP CVD apparatus

2A to 2C are views illustrating a process of generating voids in a gapfill process

3 illustrates an HDP CVD apparatus according to an embodiment of the present invention.

4 is a waveform diagram of a pulse RF;

5 is a flowchart illustrating a gapfill method according to an embodiment of the present invention.

Description of the Related Art [0002]

10,100: HDP CVD apparatus 11: chamber

12 substrate holder 13 gas injector

14: RF antenna 15: source RF power

16 source matching circuit 17 bias RF power supply

18: matching circuit for bias 19: DC electrode

20: DC power supply 30: pulse RF

The present invention relates to a gap-fill (gap-fill) process of the manufacturing process of a semiconductor device, and more particularly to a method for applying a bias RF power to the substrate support of the gap fill device in a pulse to improve the gap fill performance.

In recent years, as the integration of semiconductor devices has increased, the line widths and inter-device spacings of metal wirings have decreased, so that they have to be filled when forming inter-device separators, inter-metal dielectrics (IMDs), and inter-layer dielectrics (ILDs). The width of trenches and holes (hereinafter referred to as "gaps") is decreasing gradually, and therefore, even in the gap fill process, excellent process characteristics are required.

The gap fill can be achieved through various methods. However, as the aspect ratio of the gap increases, a high density plasma chemical vapor deposition (HDP CVD) method that generates high density plasma and realizes excellent gap fill characteristics is mainly used. .

1 is a sectional view schematically showing the configuration of a general HDP CVD apparatus 10. The HDP CVD apparatus 10 includes a chamber 11 forming a constant reaction space, a substrate stabilizer 12 installed inside the chamber 11, and a peripheral portion of the substrate stabilizer 12 on which the substrate w is placed. It is installed on the symmetrical gas injector 13 for injecting the process gas.

The chamber 11 is formed by coupling an insulator that separates the inside and the outside of the chamber from the top of the chamber body, and an RF antenna 14 serving as a plasma generation source is installed on the top of the chamber 11.

The RF antenna 14 may be provided with a capacitively coupled electrode or an inductively coupled electrode according to a method of forming a plasma. In the capacitively coupled electrode, the electrode is provided with the substrate support 12 as the counter electrode, the inductively coupled electrode is installed outside the chamber 11, and a dielectric is interposed with the internal space of the chamber 11.

The RF antenna 14 is connected to the source RF power source 15. On the other hand, a bias RF power source 17 for controlling the energy of ions incident on the substrate w is connected to the substrate support 12.

Typically, a frequency of 400 KHz, 2 MHz, 13.56 MHz, or 27.12 MHz or more is used for the source RF power supply 15, and a frequency of 13.56 MHz or 2 MHz or less is used for the bias RF power supply 17.

At the ends of the source RF power supply 15 and the bias RF power supply 17, a source matching circuit 16 and a bias matching circuit 18 for matching impedance are provided, respectively.

Meanwhile, in order to closely adhere the substrate w to the substrate support 12 using electrostatic force, a DC electrode 19 made of metal such as tungsten is installed inside the substrate support 12, and the DC electrode 19 is provided. Is connected to a separate DC power supply 20.

In the case where the substrate w is processed in a low temperature process, a cooling flow path (not shown) may be formed so that the coolant flows in the substrate support 12 to maintain the temperature of the substrate w at a low temperature. Helium (He) gas or the like is supplied to the rear surface of the substrate w and the surface of the substrate stabilizer 12 so as to provide efficient heat transfer between the substrate w and the substrate stabilizer 12.

Referring to the process of gap fill in the HDP CVD apparatus 10 as follows.

First, the substrate w, which is to be subjected to the gap fill process, is placed on the substrate support 12 and the non-reactive gas is injected into the chamber 11 while the source RF power source 15 is applied to the RF antenna 14 to generate plasma. Generate. At this time, when the plasma is stabilized, a process gas such as SiH ₄ , O _2, etc. is injected through the gas injector 13 to the upper portion of the substrate stabilizer 12, while the bias RF power source 17 is turned on.

When the plasma is formed, a potential difference is generated between the plasma and the substrate w, which is called a sheath region of the plasma. When the process gas converted into ions or active species due to the collision of electrons by the potential difference in the sheath region is accelerated toward the substrate w, and the bias RF power source 17 is applied to the substrate stabilizer 12, the potential difference is further increased. The larger, accelerated ions or active species enter the substrate w and desorb ions or active species that are already deposited on the substrate w from the substrate w. In general, deposition proceeds faster because the deposition rate is faster than the etching rate. In this case, deposition is mainly performed by active species, and etching is mainly performed by ions or electrons accelerated by the bias RF power source 17.

The reason why the deposition and etching are simultaneously performed in the conventional gap fill process is that voids are frequently generated in the gap when only the deposition process is performed.

As shown in FIGS. 2A to 2C, the voids are blocked when the inlet is blocked before the inside of the gap is completely filled due to an overhang phenomenon in which the thin film deposited around the opening of the gap gradually blocks the inlet of the gap. Occurs.

Therefore, when the deposition is performed and the ions are accelerated to properly etch the thin film deposited in the vicinity of the opening, the deposition rate in the vicinity of the opening can be lowered, thereby completing the gapfill without voids.

However, this method also shows a limitation in gap gap filling without voids in the existing gap fill process since the critical dimension of the device has been gradually reduced.

This is because as the width of the gap decreases, the rate of etch by-products generated near the openings of the gap cannot be discharged to the outside and redeposited near the openings.

The increase in the re-deposition rate in the vicinity of the opening is analyzed to be because the pressure near the gap opening is higher than the pressure inside the gap due to the ions and electrons incident on the substrate, thereby causing the by-products difficult to escape to the outside.

For this reason, when the aspect ratio of the device is increased, voids frequently occur when gap filling is performed even when deposition and etching are performed simultaneously.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a gap fill method that can be usefully applied to a device having a fine line width of 60 nm or less.

In particular, the pressure and ion energy near the gap opening can be controlled by pulse RF to prevent the by-products in the gap from being discharged to the outside due to the pressure of ions and radicals incident on the substrate in the HDP-CVD process. The purpose is to provide a method

In order to achieve the above object, the present invention comprises the steps of placing the gap formed substrate on the substrate support in the chamber; Supplying a non-reactive gas into the chamber and applying a source RF power to generate a plasma in the reaction space above the substrate; Supplying a deposition process gas to the reaction space, converting a bias RF power into pulsed RF and applying it to the substrate stabilizer; Blocking supply of the process gas and application of the bias RF power; It provides a gap-fill (Gap-fill) method comprising the step of quenching the plasma of the reaction space.

The gap fill method comprising: supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as pulse RF; And supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer using non-pulse RF.

In the gap fill method, the first step of supplying the deposition process gas to the reaction space, and applying the bias RF power to the substrate stabilizer as a non-pulse RF; Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as pulse RF; And supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as a non-pulse RF.

In the gap fill method, the bias RF power is applied to the substrate stabilizer as a pulse RF until the deposit by the deposition process gas is filled in the gap.

In the gap fill method, when the bias RF power is converted into a pulse and applied to the substrate stabilizer, the pulse is a bias RF on step in which ions are accelerated to the substrate and a bias RF off step in which ions are not accelerated to the substrate. Characterized in that.

In the gap fill method, S / D, which is a ratio of sputtering and deposition, is controlled to 0.02 to 0.3.

In the gap fill method, the pulse time is within 1 second, the duty ratio is 50% or less, and the S / D ratio is 0.05 to 0.2.

The present invention for achieving the above object is a chamber forming a constant reaction space; A substrate support installed in the chamber and on which a substrate is placed; Gas injection means for injecting a process gas into an upper portion of the substrate stabilizer; A plasma generation source disposed above the substrate stabilizer; An RF power supply for supplying impedance-matched RF power to the plasma generation source; A bias RF power supply for supplying impedance matched bias RF power to the substrate stabilizer; It provides a gap fill device comprising a; pulse RF connected between the substrate support and the bias RF power supply.

In the gap fill device, the bias RF power supply supplies RF power of 100 KHz to 30 MHz or RF power selected from 2 MHz, 13.56 MHz, and 27.12 MHz.

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

3 shows an HDP CVD apparatus 100 according to an embodiment of the present invention, the same parts as in the prior art will be denoted by the same reference numerals as in FIG.

HDP CVD apparatus 100 according to an embodiment of the present invention is a signal supplied from the bias RF power supply 17 between the bias RF power supply 17 and the bias matching circuit 18 connected to the substrate stabilizer 12 A pulse RF 30 is received to change the pulse into pulses.

When the pulse RF 30 is provided in this manner, the RF power output from the bias RF power source 17 is converted into pulses and applied to the substrate stabilizer 12 via the bias matching circuit 18.

The bias RF power source 17 contributes to accelerating ions entering the substrate stabilizer 12. 4 is a waveform diagram of the pulse RF. Referring to FIG. 4, the bias RF power applied to the substrate stabilizer 12 is periodically biased by the pulse RF 30. It turns off. In the bias RF on state, the ions are momentarily accelerated to increase the amount of ions incident on the substrate w. In the bias RF off state, the ions are not accelerated and almost no amount of ions are accelerated to the substrate w.

In the bias RF-on state, highly accelerated ions enter the gap and the opening of the substrate w, and deposition and etching are actively carried out, and the number of particles in the gap increases due to the etched by-products. This increases the number of ions that enter the gap. On the other hand, in the bias RF-off state, there is little amount of ions accelerated to the substrate w, and the pressure in the gap opening is lowered so that by-products in the gap are discharged to the outside.

In the gap formed on the substrate w, when the ions accelerate, the number of ions incident into the gap increases, and the etching by-products by the ions increase. On the other hand, when there is no acceleration force of the ions, there are almost no ions incident into the gap, and no by-products inside the gap are generated.

The change in the acceleration force of the ions incident on the gap affects the number of incident ions, and if there is little number of incident ions, the by-products in the gap form a condition that can be discharged out of the gap. That is, the pressure in the vicinity of the opening of the gap is lowered so that by-products in the gap remain and can be discharged smoothly without redeposition.

When the by-products are smoothly discharged as described above, the rate of re-deposition inside the gap is greatly reduced, so that the deposition rate decreases near the opening of the gap, thereby increasing the time to fill the gap, thereby preventing the occurrence of voids.

Hereinafter, the gap fill process in the HDP CVD apparatus 100 according to the exemplary embodiment of the present invention will be described with reference to FIG. 2 and FIG. 5, which is a flowchart.

First, the substrate w having a gap formed therein is carried into the chamber 11 and placed in the substrate support 12. (ST110)

Subsequently, the inside of the chamber 11 is stabilized by injecting an unreacted gas such as Ar, He, H ₂ , or O ₂ . When the pressure inside the chamber is kept constant, the source RF power source 15 is turned on to generate plasma in the chamber 11. At this time, the frequency of the source RF power applied is selected from several hundred KHz to several tens of MHz. Generally, several hundred KHz, 2 MHz, 13.56 MHz and so on. / cm ² or less. (ST120, ST130)

When the plasma thus formed is stabilized, the process gas is injected through the gas injector 13 to the upper portion of the substrate stabilizer 12, while the bias RF power source 17 is converted into a pulse RF and applied to the substrate stabilizer 12. .

The type of process gas depends on the type of deposited thin film. For example, in the case of a silicon oxide film, a gas containing Si (eg, SiH ₄ ), O ₂ , O _3, or the like is used as the process gas. During the process gas supply, the supply of unreacted gas may be stopped or the flow rate may be adjusted continuously. The bias RF power supply 17 is provided at a frequency selected from 100 KHz to 30 MHz, preferably 2 MHz, 13.56 MHz, and 27.12 MHz. When supplying the process gas, the chamber internal pressure is preferably maintained at several to several tens of mTorr, and if necessary, a pressure of 1 mTorr or less may be maintained.

While providing the RF power supplied from the bias RF power source 17 in pulses, it is important to control the S / D which is the total ratio of the sputter and the deposition. S / D should be controlled within 0.02 ~ 0.3 and used differently depending on the thickness or aspect ratio to be applied. Use below this range can lead to overhang voids.

Duty ratio refers to the on time / pulse time (on time + off time) of the bias RF power supply. The smaller the duty ratio, the higher the gap fill capability. In the present invention, since the bias RF power source 17 is converted into a pulsed RF and applied to the substrate stabilizer 12, ions in the plasma are periodically accelerated or hardly accelerated. Therefore, when ions are accelerated, the amount of ions incident on the substrate (w) increases, so that deposition and etching are actively performed, and when there is no acceleration, there is almost no amount of ions, and the pressure outside the gap is relatively low, so that by-products generated inside the gap are relatively low. This will discharge smoothly to the outside.

However, if the pulse time is 2 seconds or more and the duty ratio is 50% or less, the unbiased deposition interval may increase, causing voids due to overhang. In other words, the duty cycle is less than 50% within 1 second of the pulse time, and the S / D ratio of 0.05 to 0.2 is used to maximize the gap fill capability. By using this section, it is possible to prevent overhang in the unbiased deposition section and to ensure sufficient time for the by-product to be discharged to the outside. (ST140, ST150)

After the gap fill is completed, the supply of the process gas is stopped, the bias RF 17 is cut off, and the supply of the source RF power supply 15 is stopped to dissipate the plasma. Until this time, the non-reactive gas may be continuously supplied. (ST160, ST170)

Subsequently, if the non-reacted gas is continuously supplied, the supply of the non-reacted gas is also stopped, and the substrate (w) which has been processed is carried out to the outside. (ST180, ST190)

On the other hand, the operation of the pulse RF 30 at ST140 proceeds with only the step of filling the initial gap of deposition, and after the deposition is performed up to the height where the gap is filled, only the bias RF power source 17 can be used.

For example, in the initial stage of deposition, the bias RF power is converted into pulses and applied, and the pulses are not applied in the later stages. That is, the deposition step is divided into a pulse step and a non-pulse step.

Since the pulse RF is a method introduced to fill the gap, it is preferable not to make a pulse at least after the gap is filled since there is no reason for the pulse conversion to proceed after the gap fill is completed.

In another method, in order to fill the gap, the first step is smoothly filling the gap, so the process is performed by applying the non-pulse RF, and in the second step, the pulse RF is supplied and deposited to the gap filling height. The gap fill is completed, and in the third step, since the gap fill is in a state, the non-pulse RF is supplied to proceed with the process.

The running time of the first to third steps is selectively adjusted according to the structure of the gap.

According to the present invention, in the gap fill process, the bias RF power may be supplied as a pulse to periodically adjust energy and partial pressure of ions incident to the opening of the gap.

Therefore, the contributions to the deposition and etching and by-products can be smoothly escaped to the outside of the gap periodically without re-deposition, thereby greatly improving the gap fill characteristics.

Claims (9)

Placing the gap-formed substrate in a substrate stabilizer in the chamber; Supplying a non-reactive gas into the chamber and applying a source RF power to generate a plasma in the reaction space above the substrate; Supplying a deposition process gas to the reaction space, converting a bias RF power into pulsed RF and applying it to the substrate stabilizer; Blocking supply of the process gas and application of the bias RF power; Extinguishing the plasma of the reaction space; Gap-fill method comprising a The method of claim 1, Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as pulse RF; Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer with a non-pulse RF; The method of claim 1, Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer using non-pulse RF; Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as pulse RF; Supplying the deposition process gas to the reaction space and applying the bias RF power to the substrate stabilizer as a non-pulse RF; a gap fill method further comprising: 4. The method according to any one of claims 1 to 3, The gap fill method is characterized in that the bias RF power is applied to the substrate stabilizer with a pulse RF until the deposit by the deposition process gas is filled in the gap. 4. The method according to any one of claims 1 to 3, When the bias RF power is converted into a pulse and applied to the substrate stabilizer, the pulse is divided into a bias RF on step in which ions are accelerated to the substrate and a bias RF off step in which ions are not accelerated to the substrate. Gap fill method The method according to any one of claims 1 to 3, Gap-fill method to control S / D, which is the ratio of sputter and deposition, to 0.02 to 0.3 The method according to any one of claims 1 to 3, The pulse fill method is characterized in that the pulse time is within 1 second, the duty ratio is 50% or less, and the S / D ratio is 0.05 to 0.2. A chamber forming a constant reaction space; A substrate support installed in the chamber and on which a substrate is placed; Gas injection means for injecting a process gas into an upper portion of the substrate stabilizer; A plasma generation source disposed above the substrate stabilizer; An RF power supply for supplying impedance-matched RF power to the plasma generation source; A bias RF power supply for supplying impedance matched bias RF power to the substrate stabilizer; A pulse RF connected between the substrate stabilizer and the bias RF power source; Gap Fill Device comprising The method of claim 7, wherein The bias RF power supply is a gap fill device for supplying RF power selected from 100 KHz to 30 MHz or RF power selected from 2 MHz, 13.56 MHz, and 27.12 MHz.

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