Thin film formation method

Abstract

A thin film forming method according to one aspect of the present invention comprises the following steps: supplying a source gas containing a metal and a reaction gas for reacting with the source gas through a gas injection unit on a substrate placed on a substrate support frame in a process chamber, and supplying power through a plasma power unit to form a plasma environment in the process chamber, thereby pre-depositing a metal thin film on the substrate for a first time period; cutting off the power of the plasma power unit, and supplying the source gas and the reaction gas to the substrate for a second time period to pre-treat the substrate; supplying the source gas and the reaction gas on the substrate, and supplying power through the plasma power unit to form a plasma environment in the process chamber, thereby mainly depositing a metal thin film on the substrate for a third time period.

Description

Technical Field

[0001] The present invention relates to the manufacture of semiconductor elements, and more particularly, to a thin film forming method. Background Art

[0002] In the manufacture of semiconductor devices, processes using plasma are being applied. For example, plasma is used to activate process gases, thereby enabling a deposition process to be performed quickly even at low process temperatures. An example of such a process method is plasma enhanced chemical vapor deposition (PECVD).

[0003] In such a thin film deposition process using plasma, the quality of the thin film is affected by the plasma environment or the substrate surface treatment, etc. In particular, in the deposition of metal thin films, the pretreatment of the substrate before the main deposition greatly affects the impurity content in the metal thin film, etc. Summary of the invention

[0004] (Problem to be solved)

[0005] The present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a thin film forming method that can reduce the impurity content in a metal thin film. However, such a subject is exemplary and the scope of the present invention is not limited thereby.

[0006] (Methods of solving the problem)

[0007] A thin film forming method according to one aspect of the present invention comprises the following steps: supplying a source gas containing a metal and a reaction gas for reacting with the source gas through a gas injection unit on a substrate placed on a substrate support frame in a process chamber, and supplying power through a plasma power unit to form a plasma environment in the process chamber, thereby pre-depositing a metal thin film on the substrate for a first time period; cutting off the power of the plasma power unit, and supplying the source gas and the reaction gas to the substrate for a second time period to pre-treat the substrate; supplying the source gas and the reaction gas on the substrate, and supplying power through the plasma power unit to form a plasma environment in the process chamber, thereby mainly depositing a metal thin film on the substrate for a third time period.

[0008] According to the thin film forming method, the first time may be shorter than the second time and the third time.

[0009] According to the thin film forming method, in the pre-deposition step, the metal thin film may be deposited on the substrate. the following.

[0010] According to the thin film forming method, the source gas and the reaction gas may be continuously supplied onto the substrate during the pre-deposition step, the pre-treatment step, and the main deposition step.

[0011] According to the thin film forming method, the metal thin film is a thin film containing titanium, the source gas includes TiCl 4 gas, and the reaction gas may include H-containing gas.

[0012] According to the thin film forming method, during the pre-deposition step and the main deposition step, the plasma power supply unit may supply any one or both of a low frequency (LF) power and a high frequency (HF) power.

[0013] (Effects of the Invention)

[0014] According to one embodiment of the present invention configured as described above, in the formation of the thin film, the etching rate is reduced from the lower part to the upper part of the insulating layer, and a thin film forming method capable of forming a vertical pattern can be provided by a conventional etching method. Of course, the scope of the present invention shall not be limited by this effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic cross-sectional view showing an example of a substrate processing apparatus used for forming a metal thin film according to an embodiment of the present invention.

[0016] Figure 2 1 is a flowchart showing a thin film forming method according to an embodiment of the present invention.

[0017] Figure 3 It is shown Figure 2 A schematic graph of the supplied process gas and the supplied power in the method.

[0018] Figure 4 A graph showing the Cl content in the metal thin film formed according to the comparative example and the experimental example of the present invention.

[0019] Figure 5 It is a graph showing the F content in the metal thin film formed according to the comparative example and the experimental example of the present invention according to the depth.

[0020] Figure 6 It is a graph showing the Ti content in the metal thin film formed according to the comparative example and the experimental example of the present invention according to the depth.

[0021] (Explanation of Reference Numerals)

[0022] 110: Process chamber 120: Gas injection unit

[0023] 130: substrate support frame 140: plasma power supply unit

[0024] 146: Impedance matching section DETAILED DESCRIPTION

[0025] Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0026] The embodiments of the present invention are provided to more completely inform the present invention to those with common knowledge in the technical field. The following embodiments may be changed into various forms, and the scope of the present invention is not limited to the following embodiments. On the contrary, these embodiments are provided to make the disclosure of the present invention more complete and thorough and to fully convey the idea of ​​the present invention to the technicians. In addition, for the convenience and clarity of description, the thickness or size of each layer is exaggerated in the drawings.

[0027] Embodiments of the present invention are described below with reference to the accompanying drawings which schematically illustrate ideal embodiments of the present invention. In the accompanying drawings, variations in the shapes shown may be expected, for example, based on manufacturing techniques and / or tolerances. Thus, embodiments of the present inventive concept are not limited to the specific shapes of the regions shown in this specification, and should include variations in shapes such as those caused by manufacturing.

[0028] Figure 1 FIG. 1 is a schematic cross-sectional view showing an example of a substrate processing apparatus 100 used for forming a metal thin film according to an embodiment of the present invention.

[0029] Reference Figure 1 The substrate processing apparatus 100 may include a process chamber 110 , a gas injection unit 120 , and a substrate support frame 130 .

[0030] The process chamber 110 may define a processing space 112 therein. For example, the process chamber 110 is configured to maintain airtightness and exhaust process gas in the processing space 112, and may be connected to a vacuum chamber (not shown) through an exhaust port to adjust the vacuum level in the processing space 112. The process chamber 110 may be provided in various shapes, for example, may include a sidewall portion defining the processing space 112 and a cover portion located at an upper end of the sidewall portion.

[0031] The gas injection unit 120 may be disposed in the process chamber 110 so that the process gas supplied from the outside of the process chamber 110 is supplied to the processing space 112. The gas injection unit 120 may be disposed at an upper portion of the process chamber 110 opposite to the substrate support frame 130 so that the process gas is injected onto the substrate S placed on the substrate support frame 130. The gas injection unit 120 may include: at least one inflow hole formed at an upper side or a side portion for receiving the process gas supply from the outside; and a plurality of injection holes formed downwardly from the substrate S in order to inject the process gas onto the substrate S.

[0032] For example, the gas injection unit 120 may have various shapes, such as a shower head shape, a nozzle shape, etc. In the case where the gas injection unit 120 is in the shower head shape, the gas injection unit 120 may also be coupled to the process chamber 110 in a shape that partially covers the upper portion of the process chamber 110. For example, the gas injection unit 120 may be coupled to a cover portion or a sidewall portion in the shape of a cover of the process chamber 110.

[0033] The substrate support frame 130 may be disposed in the process chamber 110 to place the substrate S on the substrate support frame 130. For example, the substrate support frame 130 may be disposed in the process chamber 110 opposite to the gas injection unit 120. Furthermore, the substrate support frame 130 may include a heater 175 therein for heating the substrate S. The heater power supply unit 180 may be connected to the heater 175 to supply power to the heater 175.

[0034] The shape of the substrate support frame 130 roughly corresponds to the shape of the substrate S, but is not limited thereto, and various shapes larger than the substrate S can be provided to stably place the substrate S. In one example, the substrate support frame 130 can be connected to an external motor (not shown) to be raised and lowered, in which case, a bellows (not shown) can also be connected to maintain airtightness. Furthermore, since the substrate support frame 130 is configured to place the substrate S on the upper portion, it can also be called a substrate placement portion. Base, etc.

[0035] Furthermore, the plasma power supply unit 140 may be connected to the gas injection unit 120 to supply power for forming a plasma environment to the inside of the process chamber 110. For example, the plasma power supply unit 140 may include at least one RF power supply to apply at least one RF (radio frequency) power to the process chamber 110. For example, the plasma power supply unit 140 may be connected to the gas injection unit 120 to apply RF power. In this case, the gas injection unit 120 may also be referred to as a power supply electrode or an upper electrode.

[0036] There may be one or more RF power sources in the plasma power supply unit 140. For example, the RF power source may include a first RF power source 142 of a first frequency band and a second RF power source 144 of a second frequency band larger than the first frequency band, so as to control the plasma environment according to the process conditions. The dual-frequency power source composed of the first RF power source 142 and the second RF power source 144 can change the frequency band according to the process conditions or process steps, and thus has the advantage of being able to accurately control the process.

[0037] Figure 1 The power source of the plasma power supply unit 140 is shown to be two RF power sources 142 and 144, but only one of the two RF power sources may be applied. Figure 1It is an example only, and the scope of the present invention is not limited thereto.

[0038] In an example of the plasma power supply unit 140 , the first RF power supply 142 may be a low frequency (LF) power supply having a first frequency band of at least 450 kHz, and the second RF power supply 144 may be a high frequency (HF) power supply having a second frequency band of at least 13.56 MHz.

[0039] More specifically, the high frequency (HF) power source is an RF power source with a large range of 5 MHz to 60 MHz and a small range of 13.56 MHz to 27.12 MHz. The low frequency (LF) power source may be an RF power source with a large range of 100 kHz to 5 MHz and a small range of 300 kHz to 600 kHz. In one embodiment, the second frequency band has a frequency range of 13.56 MHz to 27.12 MHz, and the first frequency band may have a frequency range of 300 kHz to 600 kHz.

[0040] Furthermore, the impedance matching unit 146 may be disposed between the plasma power unit 140 and the gas injection unit 120 to achieve impedance matching between the RF power source and the process chamber 110. The RF power supplied by the plasma power unit 140 is effectively transmitted to the process chamber 110 through proper impedance matching between the plasma power unit 140 and the process chamber 110 by the impedance matching unit 146 without being reflected from the process chamber 110.

[0041] Generally, the impedance of the plasma power supply unit 140 is fixed, while the impedance of the process chamber 110 is not constant, so the impedance of the impedance matching unit 146 may be determined to match the impedance of the process chamber 110 and the impedance of the plasma power supply unit 140, but the scope of the present invention is not limited thereto.

[0042] The impedance matching section 146 may be composed of a combination of two or more selected from the group of resistors, inductors and capacitors connected in series or in parallel. Furthermore, the impedance matching section 146 may adopt a switching structure of at least one variable capacitor or capacitor array to change its impedance value according to the frequency of the RF power supply and process conditions.

[0043] In some embodiments, the impedance matching unit 146 may include a tuning capacitor connected in series with the plasma power unit 140, a load capacitor connected in parallel with the plasma power unit 140, and / or an inductor connected in series with the plasma power unit 140. The tuning capacitor and the load capacitor may change their impedance values ​​to achieve impedance matching.

[0044] Optionally, the substrate support frame 130 may further include an electrostatic electrode which applies an electrostatic force to the substrate S to be fixed on an upper portion thereof. In this case, the electrostatic electrode may receive a DC power from an electrostatic power supply part.

[0045] Furthermore, the substrate support frame 130 may include a heater 175 therein, and a heater power supply unit 180 may be connected to the heater 175 to apply AC power to the heater 175. Optionally, an RF filter is connected between the heater power supply unit 180 and the heater 175 to perform an impedance matching function between the AC power of the heater power supply unit 180 and the heater 175.

[0046] The control unit 170 can control various operations of the substrate processing apparatus 100. For example, the control unit 170 can control the impedance value of the impedance matching unit 146 or the height of the substrate support frame 130, control the on / off of the plasma power supply unit 140 and the heater power supply unit 180, and control the supply of process gas to the gas injection unit 120.

[0047] Figure 2 1 is a flowchart showing a thin film forming method according to an embodiment of the present invention.

[0048] Reference Figure 2 A thin film forming method according to an embodiment of the present invention may include a pre-deposition step S10, a pre-treatment step S20 and a main deposition step S30.

[0049] Figure 3 It is shown Figure 2 A schematic graph of the supplied process gas and the supplied power in the method.

[0050] Please refer to the following Figures 1 to 3 , a thin film forming method using the substrate processing apparatus 100 is described.

[0051] Reference Figures 1 to 3In the pre-deposition step S10, a metal-containing source gas SG and a reaction gas RG for reacting with the source gas SG are supplied to a substrate S placed on a substrate support frame 130 through a gas injection unit 120 in a process chamber 110, and a power supply PP is supplied through a plasma power supply unit 140 to form a plasma environment in the process chamber 110, so that a metal film can be pre-deposited on the substrate S for a first time t1.

[0052] The pre-deposition step S10 may be a part of pre-treatment performed before formally forming a metal film on the substrate S. In the pre-deposition step S10, the source gas SG, the reaction gas RG, and the power PP are supplied for a short first time t1, thereby depositing metal on the substrate S while a plasma enhanced chemical vapor deposition (PECVD) reaction occurs, and the substrate S may be surface-treated at the same time.

[0053] Accordingly, in the pre-deposition step S10, the metal film can actually be formed to a very thin thickness. For example, in the pre-deposition step S10, the metal can be deposited Below (greater than 0). Accordingly, the first time t1 can be a short time in the range of about 1 to 3 seconds. For example, the first time t1 can be shorter than the second time t2 and the third time t3 that are connected.

[0054] In the pre-processing step S20 , the power PP of the plasma power supply unit 140 is turned off, and the source gas SG and the reaction gas RG are supplied to the substrate S for a second time t2 , so that the substrate S can be pre-processed.

[0055] The purpose of performing the pre-treatment step S20 is to supply the source gas SG onto the substrate S without being in a plasma environment, thereby forming a source gas SG environment in the process chamber 110 before the main deposition.

[0056] In the pre-treatment step S20, since no actual metal film is formed, the pre-treatment step S20 may be performed for a longer time than the pre-deposition step S10. For example, the second time t2 is longer than the first time t1, about twice as long.

[0057] In the main deposition step S30 , source gas SG and reaction gas RG are supplied onto the substrate S, and power PP is supplied via the plasma power supply unit 140 to form a plasma environment in the process chamber 110 , thereby mainly depositing a metal thin film on the substrate S for a third time t3 .

[0058] The main deposition step S30 may be a step of forming an actual metal film on the substrate S. Thus, in the main deposition step S30, a plasma enhanced chemical vapor deposition (PECVD) reaction occurs during the supply of the source gas SG, the reaction gas RG, and the power PP for the third time t3, and a metal film of a desired thickness may be formed. Although it varies depending on the thickness of the metal film, the third time t3 may be more than 10 times the first time t1.

[0059] The source gas SG may be supplied in the pre-deposition step S10, the pre-treatment step S20, and the main deposition step S30. For example, the source gas SG may be continuously supplied on the substrate S in the pre-deposition step S10, the pre-treatment step S20, and the main deposition step S30.

[0060] In another example, when there is a short rest time or buffer time between the pre-deposition step S10, the pretreatment step S20 and the main deposition step S30, the supply of the source gas SG is briefly turned off (OFF) in the middle and can be turned on (ON) during the pre-deposition step S10, the pretreatment step S20 and the main deposition step S30.

[0061] Furthermore, an inert gas may be supplied during a portion or the entire time of the pre-deposition step S10, the pre-treatment step S20, and the main deposition step S30. For example, the inert gas may include argon (Ar) gas.

[0062] In some embodiments, the metal to be formed on the substrate S may include titanium (Ti). In this case, the source gas SG includes TiCl4 gas, and the reaction gas RG includes H-containing gas. For example, the reaction gas RG may include H2 gas.

[0063] The following describes the quality of the metal thin film formed according to the comparative example and the experimental example. In the following comparative example and the experimental example, the metal thin film is an example of the result of forming a titanium thin film.

[0064] Figure 4 A graph showing the Cl content in the metal thin film formed according to the comparative example and the experimental example of the present invention; Figure 5 is a graph showing the F content in the metal thin film formed according to the comparative example and the experimental example of the present invention according to the depth; Figure 6 It is a graph showing the Ti content in the metal thin film formed according to the comparative example and the experimental example of the present invention according to the depth. Figure 4 It is the result of XPS (Xray Photoelectron Spectroscopy) analysis; Figure 5 and Figure 6 It is the result of SIMS (Secondary Ion Mass Spectroscopy) analysis.

[0065] exist Figures 4 to 6 In the comparative example (REF), there is no pre-deposition step S10, but the pre-treatment step S20 and the main deposition step S30 are performed to form a Ti thin film as a metal thin film, and the experimental examples 1 to 3 (ES1, ES2, ES3) are as follows Figure 2 The case where the pre-deposition step S10, the pre-treatment step S20 and the main deposition step S30 are performed to form a Ti thin film as a metal thin film. Experimental examples 1 to 3 (ES1, ES2, ES3) are different in the power PP supplied by the plasma power supply unit 140. Experimental example 1 (ES1) is a case where only a low frequency (LF) power supply is supplied, Experimental example 2 (ES2) is a case where only a high frequency (HF) power supply is supplied, and Experimental example 3 (ES3) is a case where both a low frequency (LF) power supply and a high frequency (HF) power supply are supplied.

[0066] Reference Figure 4 It can be seen that the chlorine (Cl) concentration in Experimental Examples 1 to 3 (ES1, ES2, ES3) is lower than that in Comparative Example (REF). More specifically, the highest Cl concentration is the lowest in Experimental Example 3 (ES3) in which both low-frequency (LF) power and high-frequency (HF) power are supplied, and decreases in the order of Experimental Example 1 (ES1) in which only low-frequency (LF) power is used and Experimental Example 2 (ES2) in which only high-frequency (HF) power is supplied.

[0067] Reference Figure 5 It can be seen that the fluorine (F) concentration is lower in Experimental Examples 1 to 3 (ES1, ES2, ES3) than in Comparative Example (ES1).

[0068] Reference Figure 6 It can be seen that compared with the comparative example (ES1), the titanium (Ti) concentration in experimental examples 1 to 3 (ES1, ES2, ES3) is increased.

[0069] Reference Figures 4 to 6 , the titanium film of Experimental Examples 1 to 3 (ES1, ES2, ES3) has a low concentration of impurities such as Cl and F and a high titanium density compared to the titanium film of the comparative example (REF). This result can be understood as follows: in the pre-deposition step S10, impurities such as Cl, F, etc. remaining in the process chamber 110 are decomposed and removed, reducing the content of such impurities in the titanium film, and conversely increasing the titanium density. Impurities such as Cl, F, etc. are the cleaning gas supplied in the cleaning step of the process chamber 110 before the metal film is deposited and remain in the process chamber 110, so the impurities can be included in the film when the film is deposited.

[0070] Based on this, adding the pre-deposition step S10 before the pre-treatment step S20 can be understood as reducing the impurity content in the titanium film and effectively improving the quality of the titanium film.

[0071] The present invention is described with reference to the embodiments shown in the drawings, but this is only exemplary, and a person with ordinary knowledge in the technical field can understand that various modifications and other equivalent embodiments can be realized thereby. Therefore, the protection scope of the present invention should be defined by the technical concept of the claims.

Claims

1. A method for forming a thin film, comprising the following steps: In a process chamber, a source gas containing a metal and a reaction gas for reacting with the source gas are supplied through a gas injection unit on a substrate placed on a substrate support frame, and a power supply unit is supplied to form a plasma environment in the process chamber, thereby performing a metal thin film pre-deposition on the substrate for a first period of time while surface treating the substrate; Cutting off the power of the plasma power supply unit, supplying the source gas and the reaction gas onto the substrate for a second time period to pre-treat the substrate; The source gas and the reaction gas are supplied on the substrate, and power is supplied through the plasma power supply unit to form a plasma environment in the process chamber, and then a metal thin film is deposited on the substrate for a third time period. The first time is shorter than the second time and the third time, The thickness of the metal film formed in the pre-deposition step is thinner than the thickness of the metal film formed in the main deposition step, The third time is more than 10 times the first time, During the pre-deposition step and the main deposition step, the plasma power supply unit supplies both low-frequency power and high-frequency power.

2. The thin film forming method according to claim 1, characterized in that: In the pre-deposition step, the metal film is deposited on the substrate. the following.

3. The thin film forming method according to claim 1, characterized in that: During the pre-deposition step, the pre-treatment step, and the main deposition step, the source gas and the reaction gas are continuously supplied onto the substrate.

4. The thin film forming method according to claim 1, characterized in that: The metal film is a titanium-containing film, The source gas comprises TiCl4 gas, The reaction gas includes a H-containing gas.

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