Method for forming a thin film

Abstract

The present invention provides a substrate processing method for filling gaps without seams or voids, the method comprising: providing a substrate having gaps in a reaction chamber, evacuating the reaction chamber to a pressure of 5 Torr or less, and filling the gaps with a film by alternately and sequentially supplying precursors, reactants, and radio frequency electromagnetic radiation comprising a relatively high radio frequency component and a relatively low radio frequency component.

Description

Technical Field

[0001] The present disclosure provides a method for filling a gap, and more particularly, provides a method for filling a gap without seams or voids. Background Art

[0002] In a gap filling process for a semiconductor manufacturing process, an atomic layer deposition or a plasma enhanced atomic layer deposition method can be used to deposit a uniform film without seams and / or voids on a deep bottom portion of a pattern. When the trench undergoes a subsequent heat treatment, cracks may appear in the film filling the trench.

[0003] Figure 1 Shows cracks that appear in the film filling the gap and spread to the top surface of the trench during a subsequent heat treatment. In Figure 1 In a subsequent heat treatment step after filling the gap, shrinkage stress acts on the film toward the side surface of the trench and generates void 1 or crack 2. Therefore, the film may need to be dense and hard to minimize film shrinkage, especially the film on the side surface of the trench. Generally, film shrinkage may be inversely proportional to the wet etch resistance. That is, a film with high wet etch resistance may be dense and shrink less, but a film with low wet etch resistance may be less dense and shrink more. Therefore, by controlling the wet etch resistance, film shrinkage can be controlled.

[0004] Radicals in a plasma process can be used to make the film denser and improve the wet etch resistance because the radicals enhance the ion bombardment effect on the film. For example, when the film is deposited on the inner surface of the trench in a gap filling process, radio frequency electromagnetic radiation is supplied. For example, a higher radio frequency electromagnetic radiation such as RF power and / or a longer radio frequency electromagnetic radiation supply time can be applied to make the film denser and improve the wet etch resistance of the film.

[0005] Figure 2 Shows the wet etch rate (WER) of the SiO 2 film at each position of the trench where cracks appear in the film. As Figure 2 shown in 2 the wet etch resistance of the SiO 2 in the top portion of the trench can be higher and denser than that of the SiO

[0006] Increasing the RF power can generate parasitic plasmas inside / around the reaction space and trigger unsafe situations, such as RF power discharging outside the substrate processing equipment, and increasing the RF power supply time can reduce productivity. Additionally, as the aspect ratio of the trench may increase, it may be more difficult for radicals to reach the bottom portion of the trench. Accordingly, the present invention provides a method that makes the film denser and improves the wet-etch resistance of the film in the bottom portion of trenches with high aspect ratios, prevents cracks from occurring in the film, and does not trigger safety issues and does not reduce productivity. SUMMARY OF THE INVENTION

[0007] The present disclosure provides a method for filling gaps and forming a film with high wet-etch resistance.

[0008] In one embodiment according to the present disclosure, the gap is filled by providing a substrate having trenches in a reaction chamber, evacuating the reaction chamber to a pressure of 5 Torr or less, and alternately and sequentially supplying a precursor and a reactant, wherein the reactant is activated by supplying radio frequency electromagnetic radiation comprising a relatively high radio frequency component and a relatively low radio frequency component.

[0009] In another embodiment according to the present disclosure, the gap is filled by providing a substrate having trenches in a reaction chamber, evacuating the reaction chamber to a pressure of 5 Torr or less, and alternately and sequentially supplying a precursor and a reactant, wherein the reactant is activated by radio frequency electromagnetic radiation comprising a relatively high radio frequency component and a relatively low radio frequency component, wherein the relatively high radio frequency and the relatively low radio frequency portions overlap.

[0010] In another embodiment according to the present disclosure, the gap is filled by providing a substrate having trenches in a reaction chamber, evacuating the reaction chamber to a pressure of 5 Torr or less, and alternately and sequentially supplying a precursor and a reactant, wherein the reactant is activated by radio frequency electromagnetic radiation comprising a relatively high radio frequency component and a relatively low radio frequency component, wherein the relatively high radio frequency component and the relatively low radio frequency component RF power are supplied in the form of pulses having a duty cycle of about 10% to 75%.

[0011] In another embodiment according to the present disclosure, the gap is filled by providing a substrate having trenches in a reaction chamber, evacuating the reaction chamber to a pressure of 5 Torr or less, and alternately and sequentially supplying a precursor and a reactant, wherein the reactant is activated by radio frequency electromagnetic radiation comprising a relatively high radio frequency component and a relatively low radio frequency component, wherein the power ratio of the high radio frequency component and the low radio frequency component is adjusted to about 1:1 to 3:1 to form a film with uniform density throughout the gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a view of gap filling and its problems according to an existing substrate processing method.

[0014] Figure 2 is a view of the difference in WER of the SiO 2 film at each position in the gap when cracks occur.

[0015] Figure 3 is a view of the concept of an existing substrate processing method and a substrate processing method according to an embodiment.

[0016] Figure 4A and Figure 4B is a view of the more detailed processing sequence of an existing substrate processing method and a substrate processing method according to an embodiment.

[0017] Figure 5 is a diagram showing the WER of the SiO 2 film according to pressure depending on the position in the gap.

[0018] Figure 6 is a diagram showing the WER of the SiO 2 film according to the low RF component depending on the position in the gap.

[0019] Figure 7 is a diagram showing the WER of the SiO 2 film according to the process pressure and RF component at the side bottom part of the gap.

[0020] Figure 8A and Figure 8B is a view according to another embodiment of the present disclosure.

[0021] Figure 9 is a view of the duty cycle.

[0022] Figure 10 is a view of a substrate processing apparatus for processing a substrate according to the present disclosure. Detailed Description

[0023] In one embodiment according to the present disclosure, dual RF electromagnetic radiation and low process pressure may be applied to form a film in a gap.

[0024] Figure 3 Schematically shows one embodiment of a substrate processing method according to the present disclosure. The film may be deposited by the PEALD method. Figure 3 A may be a PEALD process using a single frequency RF power, andFigure 3 B can be a PEALD process using dual radio frequency electromagnetic radiation. In Figure 3 B, a relatively high radio frequency component having a frequency of 13.56 MHz and a relatively low radio frequency component having a frequency of 430 kHz can be provided to the process. According to Figure 3 the substrate processing method of B can be performed at a process pressure lower than Figure 3 the process pressure of the process in A. That is, in the process, regardless of the depth of the trench, a relatively high radio frequency component can be applied to have uniform wet etching resistance. This can increase the density of free radicals and the ion bombardment effect, so that the density of the film can be increased. A relatively low radio frequency component can also be applied to increase the mean free path of the free radicals. The process according to the present disclosure can be carried out at a low process pressure to reduce the collision probability between free radicals and other gas molecules, so that more free radicals can reach the bottom part of the gap. Therefore, by combining the above three factors, namely a relatively high radio frequency component, a relatively low radio frequency component, and a low process pressure, more free radicals can reach the bottom of the gap and a denser film can be uniformly formed in the bottom part of the gap.

[0025] FIG. 4 shows in more detail Figure 3 the process sequence. FIG. 4 illustrates the process sequence of depositing a SiO 2 film on a substrate by PEALD. Figure 4A is an existing substrate processing method in which a Si precursor is intermittently provided and an oxygen reactant and an Ar purge gas are continuously provided. The 13.56 MHz high radio frequency component of the radio frequency electromagnetic radiation is only intermittently supplied in situ, and the oxygen gas is activated to react with the silicon molecules adsorbed on the substrate to form a SiO 2 film in the radio frequency component supply step. Figure 4B is a substrate processing method according to the present disclosure, in which not only the 13.56 MHz high radio frequency component of the radio frequency electromagnetic radiation is supplied, but also the 430 kHz low radio frequency component of the radio frequency electromagnetic radiation is simultaneously supplied. In Figure 4B the process pressure is lower than Figure 4A the process pressure in. The high radio frequency component and the low radio frequency component can be supplied in situ as shown in FIG. 4, but the high radio frequency component and the low radio frequency component can be remotely supplied, or at least one of the high radio frequency component and the low radio frequency component can be supplied in situ.

[0026] As described above, the high radio frequency component increases the free radical density and the ion bombardment effect, and helps to form a dense film accordingly. The low radio frequency component increases the mean free path of the ions, so that a wide range of the film can be uniformly densified. The low process pressure reduces the collision probability between free radicals and other gas molecules, so that more free radical ions can reach the bottom of the gap. By combining these three factors, more free radicals reach the bottom of the gap, and a dense film can be uniformly formed throughout the gap. InFigure 4B In this process, the substrate treatment sequence is repeated N times until the gap is filled with SiO 2 film.

[0027] Table 1 below shows the detailed experimental conditions according to another embodiment of the present disclosure.

[0028] Table 1 Process Conditions

[0029]

[0030] As described in Table 1, the SiO 2 film can be formed at 550 °C between a process pressure of 3 Torr and 5 Torr. The SiO 2 film can be formed by supplying a silicon-containing precursor and an oxygen reactant. The silicon-containing precursor can be an aminosilane precursor. However, the silicon precursor is not limited thereto, and silicon halides and iodosilanes can be used as the silicon-containing precursor. For example, DIPAS, SiH 3 N(iPr) 2 , TSA, (SiH 3 ) 3 N, DSO, (SiH 3 ) 2 , DSMA, (SiH 3 ) 2 , DSEA, (SiH 3 ) 2 , Net, DSIPA, (SiH 3 ) 2 , DSTBA, (SiH 3 ) 2 , N(tBu), DEAS, SiH 3 NEt 2 , DTBAS, SiH 3 N(tBu) 2 , BDEAS, SiH 2 (NEt 2 ) 2 , BDMAS, SiH 2 (NMe 2 ) 2 , BTBAS, SiH 2 (NHtBu) 2 , BITS, SiH 2 (NHSiMe 3 ) 2 , TEOS, Si(OEt) 4 , SiCl 4 , HCD, Si 2 Cl 6 , 3DMAS, SiH(N(Me) 2 )3 , BEMAS, SiH2[N(Et)(Me)] 2 , AHEAD, Si 2 (NHEt) 6 , TEAS, Si(NHEt) 4 , Si 3 H 8 , DCS, SiH 2 Cl 2 , SiHI 3 , SiH 2 I 2 can be used as silicon-containing precursors, and at least one of these precursors can be provided to a substrate. In addition to oxygen, O 3 , N 2 O and CO 2 can be provided as reactants. The oxygen reactant can act as a reactive purge gas so that oxygen can be continuously provided to the substrate and activated by radio frequency electromagnetic radiation, and react with silicon molecules adsorbed on the substrate to become a silicon oxide layer, but when no radio frequency electromagnetic radiation is provided and only the reaction by-products and the reaction space are purged, it does not react with silicon molecules. In the process, a high radio frequency component of 900 to 1200 W and a low radio frequency component of 0.1 to 300 W are simultaneously supplied to the reaction space. The hardness or density of the SiO 2 film deposited in the gap is measured by measuring the wet etching rate of the film. In the present invention, the WER (wet etching rate) is measured by immersing the sample in a dilute HF solution (100:1) for one minute.

[0031] Figure 5 shows the wet etching rate of the SiO 2 film at each position of the gap after filling the gap with the SiO 2 film and then performing wet etching according to the conditions in Table 1. In Figure 5 , the substrate processing process is carried out under the common condition of supplying a 900 W high radio frequency component for one second at process pressures of 3 Torr and 5 Torr, respectively. As shown in Figure 5 , as the gap becomes deeper, the WER of the SiO 2 film becomes higher. This indicates that the resistance to wet etching in the bottom part of the trench is lower than the wet etching rate of the top part, and the mobility of the radicals is inversely proportional to the depth of the gap. Figure 5 also shows that the resistance to wet etching at the side bottom part varies greatly depending on the process pressure. That is, at a low process pressure, the resistance to wet etching of the film at the side bottom part of the gap is improved more because at a low process pressure, the collision between the radicals and other gas molecules is reduced, and more radicals reach the bottom part of the gap. According to Figure 5, compared with the wet etching resistance at 5 Torr, the wet etching resistance of the SiO at the side bottom part of the gap at 3 Torr can be improved by about 31%. 2 The wet etching resistance of the film can be improved by about 31%.

[0032] Figure 6 Shows that under the common conditions of a 3 Torr process pressure, a 1200 W high RF component, and a 1-second RF supply time, according to the power of the low RF component, at each position of the gap, the SiO deposited on the inner wall of the gap 2 The WER of the film. The high RF component and the low RF component can be supplied for 1 second. More specifically, Figure 6 Shows the WER when the power of the low RF component is 0 W (no LRF), 100 W, and 300 W respectively, where a 1200 W high RF component is supplied for 1 second.

[0033] In the case where the low RF component is not supplied, the case of 0 W of the low RF component is equivalent to the process result performed at 3 Torr in Figure 6 The same pressure as Figure 5 Among them, when the high RF component can be increased from 900 W ( Figure 5 ) to 1200 W ( Figure 6 ), the wet etching rate of the SiO at the side bottom part of the gap 2 The film can be reduced from 7.9 to 6.5. In other words, when only the high RF component is supplied, by increasing the ion bombardment effect, the wet etching resistance can be improved, and a denser film can be deposited.

[0034] Figure 6 Shows that the more the low RF component power increases from 100 W to 300 W, the more the wet etching resistance at the bottom part of the trench can be improved accordingly. Figure 6 Also shows that the more the low RF component power can be increased, the more the difference in wet etching resistance between the side top, side middle, and side bottom can be reduced, and the wet etching resistance (or wet etching rate) between them becomes uniform. For example, when the low RF component power can be increased from 0 W to 100 W to 300 W, the wet etching rate of the SiO at each part 2 The film is 3.4 at the side top part, 3.7 at the side middle part, and 4.6 at the side bottom part, thus reducing the difference in wet etching rate.

[0035] Figure 7 Shows the trend of the wet etching rate (or wet etching resistance) of the SiO at the side bottom part of the trench according to the process pressure, high RF component power (HRF power), and low RF component power (LRF power), where both RF component powers are supplied for 1 second. In 2 The wet etching rate (or wet etching resistance) of the film. In Figure 7In [context], when a low process pressure, a high radio frequency (RF) component power, and a low RF component power are applied simultaneously, the wet etch resistance can be maximized, and the film can be much denser. For example, when the high RF component power and the low RF component power are both supplied at 3 Torr, i.e., under condition d, the wet etch resistance can be improved by about 55% compared to that under 5 Torr, i.e., condition a. Therefore, by combining a high RF component and a low RF component at a low process pressure, a film with high and more uniform wet etch resistance can be deposited on the inner wall of the gap.

[0036] In Figure 7 [context], under condition d with a pressure of 3 Torr, the wet etch resistance of the film at the lower part of the sidewall of the gap can be the lowest and the degree of densification can be the highest, and the high RF component power and the low RF component power are 1200 W and 300 W respectively, i.e., an RF component power ratio of 3:1. However, the ratio of the high RF component power to the low frequency component power is not limited to this. The high RF component power and the low RF component power can be provided within a ratio range of 1:1 to 3:1.

[0037] According to the above Figures 5 to 7 and the process results in Table 1, it may be desirable to maintain the process pressure at less than 3 Torr and increase the power of the high RF component and the low RF component within the range of not generating parasitic plasma around the reactor and not emitting RF electromagnetic radiation outside the reactor, so that free radicals can reach the bottom part of the gap and contribute to the formation of a dense film. It is also desirable to provide the high RF component power and the low RF component power within a ratio range of 1:1 to 3:1. Therefore, gaps with a high aspect ratio greater than 20:1 can be particularly uniformly filled with a dense film.

[0038] In Table 1, Figures 5 through 7 [context], a high RF component of 13.56 MHz and a low RF component of 430 kHz (= 0.43 MHz) can be provided, but it is not limited to this. In another embodiment, a high RF component within the range of 12 MHz to 60 MHz and a low RF component within the range of 0.3 MHz to 2 MHz can be provided.

[0039] In addition to Figure 4, Figure 8 illustrates other embodiments. In Figure 8A the RF electromagnetic radiation supply step in [context], the high RF component is supplied first, and then the low RF component is supplied sequentially. This allows free radicals to move to the gap after being generated in the reaction space, giving the free radicals enough time to reach the bottom of the gap. In Figure 8A [context], the high RF component and the low RF component are supplied sequentially, but in another embodiment, they can overlap. That is, the supply of the low RF component can start before the end of the supply of the high RF component.

[0040] In Figure 8BIn another embodiment, the high RF component and the low RF component are supplied in pulse form, and the duty cycle, i.e., the ratio of the plasma on / off time, can be set such that the plasma damage to the substrate caused by radicals and active ions can be reduced. Therefore, in addition to the technical advantages according to FIG. 4, the embodiment of FIG. 8 can also have another technical advantage. In another embodiment, at least one of the high RF component and the low RF component can be supplied in pulse form.

[0041] When the RF electromagnetic radiation is provided in pulse form, the duty cycle can be defined as the ratio of the actual RF electromagnetic radiation supply time to the unit cycle time of the RF electromagnetic radiation pulse.

[0042] Figure 9 Illustrates the definition of the duty cycle of the RF electromagnetic radiation supply step in the PEALD process. When the RF electromagnetic radiation is provided in pulse form, the ratio of the actual RF electromagnetic radiation supply time b to the unit cycle time a of the RF electromagnetic radiation pulse, i.e., b / a, is defined as the duty cycle. In another embodiment according to the present invention, the RF electromagnetic radiation can be provided in pulse form within a duty cycle range of 10% to 75%.

[0043] In another embodiment, the ratio of the high RF component and the low RF component can be adjusted to form a film with uniform density throughout the gap. Figure 10 Schematically illustrates a reactor structure for using the method. In Figure 10 , the gas supply unit 3 and the substrate support unit 4 are spaced apart and face each other, and the space therebetween forms a reaction space 13. The gas supply unit 3 can be metallic and can be a showerhead. The RF rod 14 is provided on one side of the gas supply unit 3. The RF rod 14 is provided between the RF electromagnetic radiation generation unit 9 and the gas supply unit 3, and delivers the RF electromagnetic radiation generated in the RF electromagnetic radiation generation unit 9 to the gas supply unit 3. The substrate support unit 4 can be a heating block, and can include a substrate loading unit (not shown) thereon. The substrate support unit can be a pedestal. The gas inlet 5 can be connected to one side of the reactor wall 2 surrounding the reactor 1 through the reactor wall 2. The gas can be supplied to the substrate 6 through the gas inlet 5, the gas supply unit 3, and the reaction space 13. The reaction by-products can be discharged through the exhaust path 7 connected to the other side of the reactor 2 and the exhaust unit 8 that can include an exhaust pump.

[0044] In Figure 10 , the RF electromagnetic radiation generation unit 9 can include a high RF component power generator 10, a low RF component power generator 11, and a matching network 12. The RF component power generated in the RF component power generators 10, 11 can be delivered to the gas supply unit 3 through the matching network and the RF rod 14. In Figure 10Among them, the gas supply unit 3 is the upper electrode, and the substrate support unit 4 facing the gas supply unit 3 is the lower electrode, and plasma is generated in the reaction space 13 by activating the gas supplied thereto.

[0045] Without excessive increase in the radio frequency electromagnetic radiation supply time and its power, a film having uniform wet etching resistance can be formed on the inner walls of trenches having a high aspect ratio by combining a high radio frequency component and a low radio frequency component at a low process pressure. Therefore, gaps, voids, or cracks in the film filling the gaps can be prevented from occurring in a subsequent heat treatment step.

Claims

1. A substrate processing method, comprising: Providing a substrate having trenches in a reaction chamber; Pumping the reaction chamber to a pressure of 5 Torr or less; and Filling the trenches with a film by a deposition cycle, the deposition cycle comprising: Supplying a precursor; Continuously supplying a reactant; Supplying radio frequency electromagnetic radiation comprising a high radio frequency component and a low radio frequency component; and Repeating the deposition cycle until the trenches are filled with the film, wherein the frequency of the high radio frequency component is from 12 to 60 MHz and the frequency of the low radio frequency component is from 0.3 to 2 MHz.

2. The method according to claim 1, wherein the method comprises simultaneously providing the high radio frequency component and the low radio frequency component.

3. The method according to claim 1, wherein the method comprises sequentially providing the high radio frequency component and the low radio frequency component.

4. The method according to claim 2, wherein at least one of the high radio frequency component and the low radio frequency component is supplied in the form of pulses having a duty cycle of 10% to 75%.

5. The method according to claim 1, wherein the reaction chamber is pumped to a pressure of less than 4 Torr.

6. The method according to claim 5, wherein the reaction chamber is pumped to a pressure of less than 3 Torr.

7. The method according to claim 1, wherein the precursor is at least one of aminosilane, iodide silane, and silicon halide or a combination thereof.

8. The method according to claim 7, wherein the precursor is at least one of the following: DIPAS, TSA, DSO, DSMA, (SiH 3 ) 2 NMe, DSEA, (SiH 3 ) 2 NEt, DSIPA, (SiH 3 ) 2 N(iPr), DSTBA, (SiH 3 ) 2 N(tBu), DEAS, DTBAS, SiH 3 N(tBu) 2 , BDEAS, SiH 2 (NEt 2 ) 2 , BDMAS, SiH 2 (NMe 2 ) 2 , BTBAS, SiH 2 (NHtBu) 2 , BITS, SiH 2 (NHSiMe 3 ) 2 , TEOS, Si(OEt) 4 , SiCl 4 , HCD, Si 2 Cl 6 , 3DMAS, SiH(N(Me) 2 ) 3 ; BEMAS, SiH 2 [N(Et)(Me)] 2 ; AHEAD, Si 2 (NHEt) 6 ; TEAS, Si(NHEt) 4 ; Si 3 H 8 ; DCS, SiH 2 Cl 2 ; SiHI 3 , SiH 2 I 2 or a combination thereof.

9. The method according to claim 1, wherein the reactant is at least one of the following: O 2 , O 3 , N 2 O and CO 2 or a combination thereof.

10. The method according to claim 1, wherein the method comprises purging between supplying the precursor or the reactant and supplying the radio frequency electromagnetic radiation.

11. The method according to claim 1, wherein the method comprises continuously providing the reactant throughout the cycle.

12. The method according to claim 5, wherein the wet etching rate and density of the film filling the gap are uniform throughout the trenches.

13. The method according to claim 1, wherein at least one of the high radio frequency component and the low radio frequency component is supplied in-situ.

14. The method according to claim 1, wherein the power ratio of the high radio frequency component and the low radio frequency component is from 1:1 to 3:1 to form a film having a uniform density throughout the trenches.

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