Film formation method and plasma processing method

Abstract

To provide a deposition method and a plasma processing method that enable formation of a film with good film quality, low etch rate, and good sidewall coverage for protecting a sidewall of a pattern.SOLUTION: To enable the formation of a film with good film quality, low etch rate, and good sidewall coverage for protecting a sidewall of a pattern, a deposition method has a first step of supplying gas to a vacuum processing chamber and generating plasma, and forming a film on the surface of a substrate to be processed by the generated plasma; after the first step, the second step of removing halogen elements by plasma, and after the second step, a third step of oxidizing or nitriding the film by plasma.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for forming a film on a semiconductor substrate and a method for plasma processing. [Background technology]

[0002] In recent years, in the semiconductor process, a technique for protecting the sidewalls of patterns has become necessary in order to form patterns with a fine pitch of less than 10 nm.

[0003] Existing film formation technologies include 1) plasma CVD, which uses plasma or other such means to simultaneously supply two or more types of molecules, film-forming species and reactive species, into a chamber to form a film, and 2) plasma atomic layer deposition (plasma ALD), which alternately supplies film-forming species (adsorbed species) and reactive species and converts only the reactive species into ions or neutral radicals using plasma to form a film.

[0004] Patent Document 1 discloses a technique in which a precursor (a silicon-containing gas) is flowed while neutral radical oxygen is constantly flowing, and plasma activation is performed after purging.

[0005] Patent Document 2 discloses a commonly known plasma ALD sequence.

[0006] Non-Patent Document 1 discloses a plasma overlap pulse CVD sequence in which tetrachlorosilane (SiCl4) is introduced first while oxygen (O2) is constantly supplied, and plasma is generated with a delay. In this sequence, the film formation rate is not temperature dependent, but the HF wet etch rate increases (deteriorating film quality) at low temperatures below 100°C.

[0007] In Non-Patent Document 2, the commonly known ALD and plasma ALD sequences are shown in FIG. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Publication US 2015 / 0110968 A1 [Patent Document 2] US Patent Publication US 2013 / 0084714 A1 [Non-patent literature]

[0009] [Non-Patent Document 1] Pieter C. Rowlette, et al., "Digital Control of SiO2 Film Deposition at Room Temperature", THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 2009,113,6906-6909 [Non-patent document 2] Seung-Woo Choi, et al., "Plasma Enhanced Atomic Layer Deposition of Al2O3 and TiN", Journal of Korean Physical Society, Vol.42, February 2003, pp.S975~S979 Summary of the Invention [Problem to be solved by the invention]

[0010] The technology disclosed in Patent Document 1 constantly oxidizes the precursor, and is a film formation method that is intermediate between CVD and ALD. Therefore, it is effective for precursors containing carbon gases that are easily volatilized by oxygen, but is less effective for other gas species, and it is presumed that the film quality may deteriorate.

[0011] The method disclosed in Patent Document 2 has the advantage that very good coverage can be obtained if the precursor is selected, but has the problem of a slow film formation rate.

[0012] In the method disclosed in Non-Patent Document 1, the etching rate can be improved (decreased) by slowing down the film formation rate, but there is a trade-off between the film formation rate and the etching rate.

[0013] In a typical plasma ALD sequence such as that disclosed in Non-Patent Document 2, plasma is generated once per cycle.

[0014] When plasma CVD, an existing film deposition technology, is used as a means of forming fine-pitch patterns while protecting the sidewalls, the film deposition rate is fast, but there is a problem of overhang formation when depositing films on fine-pitch patterns of less than 10 nm. Furthermore, conventional plasma ALD has a problem of good coverage but slow film deposition rate (a trade-off between film deposition rate and coverage).

[0015] Furthermore, the aminosilane gas species typically used in ALD are highly reactive even at room temperature, and are prone to becoming foreign matter.

[0016] To form a pattern with a fine pitch of less than 10 nm, it is necessary to solve the trade-off between film formation speed and coverage, the problems of etching resistance and foreign matter that exist in existing technologies, and to satisfy the needs for forming a film with good film quality, a low etch rate, and good sidewall coverage; however, none of the above-mentioned conventional technologies can meet these needs.

[0017] The present invention solves the above-mentioned problems of the conventional technology and provides a film forming method and a plasma processing method that enable the formation of a film with good film quality, a low etch rate, and good sidewall coverage for protecting the sidewalls of a pattern. [Means for solving the problem]

[0018] In order to solve the problems of the prior art described above, the present invention provides a film formation method including a first step of supplying a gas into a vacuum processing chamber and generating plasma, and using the generated plasma to form a film on the surface of a substrate to be processed; a second step of removing halogen elements using plasma after the first step; and a third step of oxidizing or nitriding the film using plasma after the second step.

[0019] In addition, in order to solve the problems of the conventional technology described above, the present invention provides a film formation method including a first step of supplying a gas into a vacuum processing chamber for a predetermined time, generating plasma, and forming a film on the surface of a substrate to be processed using the generated plasma; a second step of removing halogen elements using plasma after the first step; and a third step of oxidizing or nitriding the film using plasma after the second step.

[0020] Furthermore, in order to solve the problems of the prior art described above, the present invention provides a plasma processing method including a first step of supplying a gas into a vacuum processing chamber and generating plasma, and using the generated plasma to form a film on the surface of a substrate to be processed; a second step of removing halogen elements using plasma after the first step; a third step of oxidizing or nitriding the film using plasma after the second step; and a fourth step of plasma etching the film to be processed after the third step.

[0021] Furthermore, in order to solve the problems of the prior art described above, the present invention provides a plasma processing method including a first step of supplying a gas into a vacuum processing chamber for a predetermined time, generating plasma, and forming a film on the surface of a substrate to be processed using the generated plasma; a second step of removing halogen elements using plasma after the first step; a third step of oxidizing or nitriding the film using plasma after the second step; and a fourth step of plasma etching the film to be processed after the third step. [Effects of the Invention]

[0022] According to the present invention, it is possible to form a film having good film quality, a low etching rate, and good sidewall coverage for protecting the sidewalls of a mask pattern formed on a substrate to be processed.

[0023] Furthermore, according to the present invention, a film for protecting the sidewalls of a mask pattern formed on a substrate to be processed can be formed inside an etching processing apparatus that plasma-etches the substrate to be processed. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 1 is a flow chart showing an outline of a protective film forming process according to an embodiment of the present invention. [Figure 3] 3A to 3C are cross-sectional views of a substrate to be processed corresponding to each step of forming a protective film according to an embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing detailed steps of forming a protective film according to an embodiment of the present invention. [Figure 5] 4 is a time chart corresponding to detailed steps of forming a protective film according to an embodiment of the present invention. [Figure 6] 1 is a graph showing the correlation between plasma A time and normalized GPC (Growth per cycle) and normalized ER (Etching rate) according to an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing the correlation between the time of plasma B and the normalized film formation rate (Normalized GPC) and the normalized etch rate (Normalized ER) according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing the correlation between the time of plasma C and the normalized film formation rate (Normalized GPC) and the normalized etch rate (Normalized ER) according to an embodiment of the present invention. [Figure 9] 1A to 1C are diagrams showing a flow of etching using a protective film according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the correlation between the time and pressure of plasma C when etching a pattern on which a protective film according to an embodiment of the present invention is formed, and undercut during subsequent etching processing. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention provides a film formation method on a semiconductor substrate that enables a film with good film quality, a low etch rate, and good sidewall coverage to be formed inside an etching apparatus for protecting the sidewalls of a mask pattern when etching is performed using a pattern having a pitch of 10 nm or less as a mask.

[0026] That is, in the present invention, plasma is generated in three steps (Plasma A, B, C) in one cycle, and purging with an inert gas is performed between Plasma A, B, and C. Plasma A uses a film-forming gas (containing silicon and halogen) to form a thin film of one to several atomic layers on the surface of the pattern. Plasma B uses a gas (containing hydrogen) to remove halogen that has been incorporated into the thin film of one to several atomic layers formed on the surface of the pattern and on the surface of the film. Plasma C uses an oxidizing or nitriding gas (containing oxygen or nitrogen) to oxidize or nitride the thin film of one to several atomic layers formed on the surface of the pattern. This cycle is repeated multiple times, thereby forming a protective film with good film quality and good coverage on the surface of the pattern.

[0027] As a result, the present invention makes it possible to achieve the desired film formation rate, etch rate (etching resistance), and coverage.

[0028] Furthermore, by using halogen silane, which has low reactivity at room temperature, as the deposition gas, it is expected that improvements can be made, such as reducing the amount of foreign matter generated when adsorbed gas remaining in the gas piping reacts with oxygen in the atmosphere.

[0029] Furthermore, by generating plasma in three stages during the process, the first stage, Plasma A, increases the film formation rate by 50 to 100 times or more, the second stage, Plasma B, improves etching resistance, and the third stage, Plasma C, improves etching resistance and improves the actual pattern shape (reducing undercuts).

[0030] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all drawings for explaining the embodiment, components having the same functions are assigned the same reference numerals, and repeated explanations thereof will be omitted as a general rule.

[0031] However, the present invention should not be construed as being limited to the description of the embodiments shown below. Those skilled in the art will readily understand that the specific configurations can be modified without departing from the spirit or intent of the present invention. [Example]

[0032] First, an example of an embodiment of the present invention is shown in Fig. 1. Here, the configuration of an ECR (Electron Cyclotron Resonance) plasma processing apparatus 1 is shown as an example.

[0033] The plasma processing apparatus 1 according to this embodiment includes a vacuum vessel 100, a shower plate 102 having a number of holes 112 formed therein for supplying gas into the vacuum vessel 100, a sample stage 103 having a heater 111 therein and on which a substrate to be processed 101 is placed, a power supply (microwave power supply) 104 for generating plasma, a microwave generation source 1141 that receives power from the plasma generation power supply 104 and generates microwaves, a rectangular waveguide 1142 that propagates the microwave power generated by the microwave generation source 1141, a microwave matching box 1143 that adjusts the microwave power propagated inside the rectangular waveguide 1142, a converter 1144 that propagates the microwave power propagated inside the rectangular waveguide 1142 to a circular waveguide 1145, a cavity 1146 that resonates the microwave power propagated from the circular waveguide 1145, and a space between the cavity 1146 and the vacuum vessel 100. the shower plate 102 and the partition plate 1148; a mass flow controller 105 for adjusting the flow rate of the gas supplied to the inside of the vacuum vessel 100; a gas line 106 for supplying the gas, the flow rate of which is adjusted by the mass flow controller 105, between the shower plate 102 and the partition plate 1148; an exhaust pipe 107 connecting the vacuum vessel 100; a pressure control valve 108 for adjusting the pressure inside the vacuum vessel 100; a pump 109 for evacuating the inside of the vacuum vessel 100 to a vacuum through the exhaust pipe 107 and the pressure control valve 108;

[0034] In the plasma processing apparatus 1 having such a configuration, with the substrate 101 to be processed placed on the sample stage 103, the inside of the vacuum chamber 100 is evacuated to a vacuum by the pump 109. When the inside of the vacuum chamber 100 has reached a predetermined vacuum level, the substrate 101 to be processed is heated to a predetermined temperature by the heater 111 inside the sample stage 103.

[0035] With the substrate 101 to be processed heated to a predetermined temperature, one or more of at least four types of gases consisting of gases A, B, C, and D are supplied between the shower plate 102 and the partition plate 1148 through the gas line 106 with their flow rates adjusted by the mass flow controller 105 controlled by the control unit 110, and are then supplied into the vacuum chamber 100 through the holes 112 in the shower plate 102.

[0036] In this state, power is applied to the electromagnet 1147 from a power supply not shown to form a magnetic field inside the vacuum vessel 100, and plasma is generated in the region 1100 between the shower plate 102 and the sample mounting stage 103 using the plasma generation power supply 104, thereby forming a film on the substrate 101 to be processed.

[0037] In this embodiment, a method for forming a film on a semiconductor substrate is provided that uses a plasma processing apparatus 1 configured as shown in FIG. 1 and enables a film with good film quality, a low etching rate, and good sidewall coverage to be formed inside the etching apparatus for protecting the sidewalls of fine patterns.

[0038] Fig. 2 shows the basic flow of the process for forming a sidewall protection film in this embodiment. Fig. 3 shows the cross-sectional shape of a silicon (Si) layer 300 on the surface of the substrate 101 to be processed and a pattern 301 formed thereon to serve as a mask for the etching process, in accordance with the basic flow of Fig. 2.

[0039] In the processing flow shown in FIG. 2, the pattern 301 formed on the surface of the target substrate 101 has a cross-sectional shape as shown in FIG. 3(a), that is, a configuration in which a pattern (silicon oxide film pattern) 301 made of a silicon oxide film is formed on a silicon (Si) layer 300.

[0040] For such a substrate 101 to be processed, first, a gas is flowed inside the vacuum chamber 100 to be adsorbed onto the surface of the silicon oxide film pattern 301, thereby adsorbing a precursor 302 as shown in Fig. 3(b) onto the surface of the silicon oxide film pattern 301 (S201). Next, Plasma A is generated inside the vacuum chamber 100, and the substrate 101 on which the precursor 302 has been formed is subjected to a first plasma treatment, thereby forming a film 303 (Fig. 3(c)) of one to several atomic layers on the surface of the silicon oxide film pattern 301 (S202).

[0041] Next, Plasma B is generated inside the vacuum chamber 100, and halogen elements (such as chlorine) contained in the formed film 303 are removed by a second plasma treatment (S203).

[0042] Furthermore, Plasma C is generated inside the vacuum chamber 100, and a third plasma treatment is performed on the film 304 (FIG. 3(d)) from which the halogen elements have been removed, to form an oxidized or nitrided film 305 (FIG. 3(e)) (S204).

[0043] By repeating the steps from S201 to S204 a predetermined number of times (S205), a target number of layers of protective films 306 (FIG. 3(f)) are formed on the surface of the silicon oxide film pattern 301.

[0044] The film forming method according to this embodiment, which has been described with reference to Figures 2 and 3, will be described in detail using the flow diagram of Figure 4 and the timing chart of Figure 5. In this embodiment, at least four types of gases, A, B, C, and D, are used, and plasma processing is performed in three steps.

[0045] First, at time t1 in FIG. 5, film forming gas A: 251 and purge gas D: 254 are supplied from the gas line 106 between the partition plate 1148 and the shower plate 102 with their respective flow rates adjusted by the mass flow controller 105, and the film forming gas A: 251 and purge gas D: 254 are supplied into the vacuum chamber 100 through the holes 112 in the shower plate 102 (S401), and this state is continued for a predetermined time (until S402 returns Yes).

[0046] This step corresponds to the precursor formation step S201 in the flow diagram of FIG. 2, and the cross-sectional shape of the substrate 101 to be processed becomes as shown in FIG. 3(b).

[0047] Next, after a predetermined time has elapsed (Yes in S402), at time t2, the plasma power: 256 is turned on to generate Plasma A: 2561 (S403), and after a predetermined time has elapsed (Yes in S404), at time t3, the plasma power: 256 is turned off to extinguish Plasma A: 2561 and stop the supply of film forming gas A: 251 (S405).

[0048] Next, with the supply of film formation gas A:251 stopped, purge gas D:254 continues to be supplied into the vacuum vessel 100, and the atmosphere inside the vacuum vessel 100 is replaced with purge gas D:254. After a predetermined time has elapsed (Yes in S406), the supply of purge gas D:254 is stopped at time t4 (S407). In this state, the inside of the vacuum vessel 100 is evacuated by pump 109 to a high vacuum state, and gas remaining inside the vacuum vessel 100 is removed from the vacuum vessel 100.

[0049] The steps from S403 to S407 correspond to the step of forming a film with Plasma A in S202 in the flow diagram of FIG. 2, and the cross-sectional shape of the substrate 101 to be processed becomes as shown in FIG. 3(c).

[0050] Next, after a predetermined time has elapsed (Yes in S408), at time t5, reactive gas B: 252 and purge gas D: 254 are supplied into the vacuum chamber 100, and plasma power: 256 is turned on to generate plasma B: 2562 inside the vacuum chamber 100 (S409).

[0051] After this state continues for a predetermined time (Yes in S410), at time t6, the plasma power 256 is turned off to extinguish the plasma B 2562, and the supply of the reactive gas B 252 is stopped (S411).

[0052] Next, with the supply of film formation gas B:252 stopped, purge gas D:254 continues to be supplied into the vacuum vessel 100, and the atmosphere inside the vacuum vessel 100 is replaced with purge gas D:254. After a predetermined time has elapsed (Yes in S412), the supply of purge gas D:254 is stopped at time t7 (S413). In this state, the inside of the vacuum vessel 100 is evacuated by pump 109 to a high vacuum state, and gas remaining inside the vacuum vessel 100 is removed from the vacuum vessel 100.

[0053] The steps from S409 to S413 correspond to the step of removing Cl from the film by Plasma B in S203 in the flow diagram of FIG. 2, and the cross-sectional shape of the substrate 101 to be processed becomes as shown in FIG. 3(d).

[0054] Next, after a predetermined time has elapsed (Yes in S414), at time t8, reactive gas C: 253 and purge gas D: 254 are supplied into the vacuum vessel 100, and plasma power 256 is turned on to generate Plasma C: 2563 inside the vacuum vessel 100 (S415).

[0055] After this state continues for a predetermined time (Yes in S416), at time t9, the plasma power 256 is turned off to extinguish the plasma C 2563, and the supply of the reactive gas C 253 is stopped (S417).

[0056] While the supply of the film forming gas B: 252 is stopped, the purge gas D: 254 continues to be supplied into the vacuum chamber 100, and the atmosphere inside the vacuum chamber 100 is replaced with the purge gas D: 254. After a predetermined time has elapsed (Yes in S418), at time t 10 Then, the supply of purge gas D:254 is stopped (S419). In this state, the inside of the vacuum vessel 100 is evacuated by the pump 109 to a high vacuum state, and gas remaining inside the vacuum vessel 100 is removed from the vacuum vessel 100.

[0057] The steps from S415 to S419 are the same as the Plasma C step S204 in the flow chart of Figure 2. This corresponds to the step of oxidizing or nitriding the film, and the cross-sectional shape of the substrate 101 to be processed becomes as shown in FIG. 3(e).

[0058] Next, after a predetermined time has elapsed (Yes in S420), it is checked whether the steps from S401 to S420 have been repeated a predetermined number of times (S421), and if the predetermined number of times has not been reached (No in S421), the process returns to S401 and executes the series of processes. On the other hand, if the predetermined number of times has been repeated (Yes in S421), the protective film formation process is terminated.

[0059] The steps from S401 to S420 correspond to the steps from S201 to S204 in the flow diagram of FIG. 2, and when the answer in S421 is Yes, the cross-sectional shape of the substrate 101 to be processed becomes as shown in FIG. 3(f).

[0060] Here, deposition gas A 251 (Gas A in FIG. 1) is a gas containing silicon and halogen, such as tetrachlorosilane; reactive gas B 252 (Gas B in FIG. 1) is a gas for removing halogen, such as hydrogen; reactive gas C 253 (Gas C in FIG. 1) is a gas that causes oxidation, nitridation, or carbonitridation, such as oxygen; and purge gas D 254 (Gas D in FIG. 1) is an inert gas, such as argon.

[0061] In this embodiment, in order to obtain a desired film quality, which will be described later, a mass flow controller 105 was installed for each gas system, as shown in FIG.

[0062] In addition, examples of gas species such as tetrachlorosilane as deposition gas A: 251, hydrogen as reactive gas B: 252, oxygen as reactive gas C: 253, and argon as purge gas D: 254 are given as examples. For example, gas species such as dichlorosilane, trichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and methyltrichlorosilane can also be used as deposition gas A: 251. Similarly, a hydrogen-containing gas such as ammonia can be used as reactive gas B: 252 to remove halogens. For reactive gas C: 253, oxygen-containing gases such as carbon monoxide, carbon dioxide, and oxygen nitride (NO) can be used to form oxide films. For nitride films, nitrogen-containing gases such as nitrogen and ammonia can be used. For carbonitride films, a mixed gas such as methane and nitrogen can be used. Furthermore, helium or the like can be used as purge gas D: 254.

[0063] Furthermore, it is desirable to shift the time t1 at which the supply of the film-forming gas A:251 to the vacuum vessel 100 begins and the time t2 at which the Plasma A:2561 is generated so that the film is formed after the gas has been sufficiently adsorbed onto the inner surface of the vacuum vessel 100, but the time t1 at which the supply of the film-forming gas A:251 to the vacuum vessel 100 begins and the time t2 at which the Plasma A:2561 is generated may be the same.

[0064] In the configuration of the plasma processing apparatus 1 shown in FIG. 1, an example of an electron cyclotron resonance (ECR) plasma source is shown, but a capacitively coupled plasma (CCP) plasma source or an inductively coupled plasma (ICP) plasma source can also be used.

[0065] Graph 600 in FIG. 6 shows the time dependence of Plasma A:2561 on a normalized film formation rate (Normalized GPC, Growth Per Cycle) 610, which is obtained by dividing the film formation rate of a film formed using the plasma processing apparatus 1 shown in FIG. 1 based on the process flow and time charts of this embodiment shown in FIGS. 2 to 5 by a desired film formation rate as a reference, and a normalized dry etch rate (Normalized ER) 620, which is obtained by dividing the dry etching rate of the formed film by a desired dry etching rate as a reference.

[0066] The etching conditions for measuring the dry etch rate were CF4 / CHF3 gas and anisotropic etching using a substrate bias, with the duration of Plasma B:2562 (the time from t5 to t6 in Figure 5) being 3 seconds and the duration of Plasma C:2563 (the time from t8 to t9 in Figure 5) being 10 seconds. The normalized GPC and normalized ER on the vertical axis, where 1 is the normalized value, are target values, and it is desirable for the normalized deposition rate 610 to be 1.0 or more (above the target value) and the normalized dry etch rate 420 to be 1.0 or less (below the target value).

[0067] From this graph, it can be seen that the normalized deposition rate 610 is more than 50 times higher when Plasma A:2561 is used (data in FIG. 6 where the Plasma A time on the horizontal axis is 1 ec or more) than when Plasma A:2561 is not used (data in FIG. 6 where the Plasma A time on the horizontal axis is 0 sec). It can also be seen that when the time for generating Plasma A:2561 is increased to 4 seconds or more, the normalized deposition rate 610 increases, but the normalized dry etch rate 620 increases sharply.

[0068] For a film such as a sidewall protection film, a lower normalized dry etch rate 620 is preferable. Therefore, it can be seen that there is a window of 1 to 3 seconds for maintaining Plasma A:2561 (the time from t2 to t3 in Figure 5) in which both the film formation rate and the etch rate can be achieved.

[0069] Graph 700 in Fig. 7 shows the time dependence of Plasma B:2562 on the normalized deposition rate (Normalized GPC, Growth Per Cycle) 710 and the normalized dry etch rate (Normalized ER) 720 of a film formed using the plasma processing apparatus 1 shown in Fig. 1 based on the process flow and time charts of this embodiment shown in Fig. 2 to Fig. 5. Here, the etching conditions for measuring the dry etch rate were CF4 / CHF3 gas, anisotropic etching using a substrate bias, and the duration of Plasma A:2561 was 1 second, and the duration of Plasma C:2563 was 10 seconds.

[0070] From this graph 700, it can be seen that the effect of the duration of Plasma B:2562 on the normalized deposition rate 710 is small, and the normalized deposition rate 710 remains almost unchanged, but the normalized dry etch rate 720 drops below the standard value (normalized dry etch rate 720 is 1 or less) when the duration of Plasma B:2562 is 3 seconds or longer.

[0071] Graph 800 in Fig. 8 shows the time dependence of Plasma C:2563 on the normalized deposition rate (Normalized GPC, Growth Per Cycle) 810 and the normalized dry etch rate (Normalized ER) 820 of a film formed using the plasma processing apparatus 1 shown in Fig. 1 based on the process flow and time charts of this embodiment shown in Fig. 2 to Fig. 5. Here, the etching conditions for measuring the dry etch rate were CF4 / CHF3 gas, anisotropic etching using a substrate bias, and the duration of Plasma A:2561 was 1 second, and the duration of Plasma B:2562 was 3 seconds.

[0072] From this graph 800, it can be seen that the effect of the duration of Plasma C:2563 on the normalized deposition rate 810 is small, and the normalized deposition rate 810 remains almost unchanged, but the normalized dry etch rate 820 falls below the normalized value (normalized dry etch rate 820 on the vertical axis is 1) when the duration of Plasma C:2563 is 10 seconds or longer.

[0073] From the above results, when the duration of Plasma A: 2561 is tA, the duration of Plasma B: 2562 is tB, and the duration of Plasma C: 2563 is tC, it can be seen that the following relationship must be established between tA, tB, and tC. tA=1~3 sec and tA≦tB≦tC FIG. 9 shows the cross-sectional shapes of a pattern at each step when a pattern having a film formed on its surface based on the processing flow and time chart of this embodiment shown in FIGS. 2 to 5 is etched using the plasma processing apparatus 1 shown in FIG. 1.

[0074] FIG. 9(a) shows a cross section of the pattern before the multilayer film is formed according to this embodiment, which corresponds to (a) of the pattern cross section shape described in FIG. 3, and has a configuration in which a silicon oxide film pattern 902 (corresponding to the silicon oxide film pattern 301 in FIG. 3) is formed on a silicon (Si) layer 901 (corresponding to the silicon (Si) layer 300 in FIG. 3).

[0075] FIG. 9(b) shows a cross section of the pattern after forming the multilayer film according to this embodiment described with reference to FIGS. 2 to 5, i.e., corresponds to (f) of the pattern cross section described in FIG. 3, and shows a state in which a multilayer protective film 903 (corresponding to the protective film 306 in (f) of FIG. 3) is formed on the surface of the silicon oxide film pattern 902.

[0076] 9(c) shows a state in which a trench pattern (or hole pattern) 910 reaching the silicon (Si) layer 901 is formed by etching the pattern after forming the multilayer film according to this embodiment described with reference to FIGS. 2 to 5. Here, the silicon oxide film pattern 902 is etched using the above-mentioned CF4 / CHF3 mixed gas, and the silicon (Si) layer 901 is etched using chlorine gas. Arrow 904 indicates the direction in which etching progresses faster when anisotropic etching is performed using a substrate bias to process the silicon oxide film pattern 902 and the silicon (Si) layer 901.

[0077] The formation of the multilayer film in FIG. 9(b) and the etching process in FIG. 9(c) can be performed using the same plasma processing apparatus.

[0078] FIG. 10 shows the relationship between each etching condition and the cross-sectional shape 1001 of the formed pattern, as well as the relationship between the results of evaluating the presence or absence of undercut 1002, when an actual etching process was performed by changing the time and pressure of Plasma C in the step (c) of FIG. 9.

[0079] Reference numeral 1010 denotes a cross-sectional shape of a silicon (Si) layer 1011 and a silicon oxide film pattern 1012 in an as-etched state, that is, when a pattern in a state in which the protective film described in this embodiment (protective film 306 in FIG. 3(f) or protective film 903 in FIG. 9) is not formed is etched to form a groove pattern 1014. From this figure, it can be seen that when the protective film described in this embodiment is not formed, a recess 1013 is formed near the interface between the silicon (Si) layer 1011 and the silicon oxide film pattern 1012 (spacer) in the portion where the groove pattern 1014 is formed, and an undercut 1002 is present.

[0080] Reference numeral 1020 indicates a case where a groove pattern 1024 is formed by etching with a duration tC of Plasma C:2563 of 10 seconds and a pressure inside the vacuum chamber 100 of 1 Pa. In this case, as in the case of 1010, a recess 1023 similar to that in 1010 is formed near the interface between the silicon (Si) layer 1021 and the silicon oxide film pattern 1022 (spacer) in the portion where the groove pattern 1024 is formed, resulting in an undercut 1002.

[0081] In contrast, when etching is performed with the duration tC of Plasma C:2563 set to 60 seconds and the pressure inside the vacuum chamber 100 set to 1 Pa to form a groove pattern 1034, as shown in 1030, no recess is formed near the interface 1033 between the silicon (Si) layer 1031 and the silicon oxide film pattern 1032 (spacer) in the area where the groove pattern 1034 is formed, and no undercut 1002 is formed.

[0082] Furthermore, as shown in 1040, when etching is performed with the duration tC of Plasma C:2563 set to 10 seconds and the pressure inside the vacuum chamber 100 set to 6 Pa to form a groove pattern 1044, as in the case of 1030, no recess is formed near the interface 1043 between the silicon (Si) layer 1041 and the silicon oxide film pattern 1042 (spacer) in the area where the groove pattern 1044 is formed, and there is no undercut 1002.

[0083] Thus, from the results of 1030 and 1040, by performing the etching process under conditions where the relationship tC*pC≧60 (sec·Pa) holds between the duration tC of Plasma C:2563 and the pressure (pC) inside the vacuum chamber 100, the etching process can be performed without undercut 1002.

[0084] From these results, it can be seen that by using the multilayer film formed by the present embodiment described with reference to Figures 2 to 5, it is possible to etch a groove or hole pattern using the silicon oxide film pattern as a mask without generating undercuts in the silicon (Si) layer.

[0085] Furthermore, according to this embodiment, the sidewall protection film of the mask pattern formed on the substrate to be processed is formed inside the etching processing apparatus that performs the plasma etching processing on the substrate to be processed, so that the process of forming the sidewall protection film and the etching processing can be carried out continuously in the same apparatus.

[0086] In addition, by using a plasma processing apparatus having a structure similar to that disclosed in the prior patent document, JP 2019-176184 A, and changing the ECR plasma surface within the same vacuum chamber, it is possible to control the amount of ions and radicals in Plasmas A, B, and C, for example, so that the amount of ions is greater than the amount of radicals in Plasma A and the amount of ions is less than the amount of radicals in Plasmas B and C, or conversely, so that the amount of ions is less than the amount of radicals in Plasma A and the amount of ions is greater than the amount of radicals in Plasmas B and C, thereby improving damage to the substrate and improving coverage.

[0087] According to this embodiment, a pattern with good coverage can be formed at a desired film formation rate and etch rate (etching resistance).

[0088] Furthermore, according to this embodiment, by using halogen silane, which has low reactivity at room temperature, as the film forming gas, it is possible to expect an improvement in that the amount of foreign matter generated by, for example, the reaction of adsorbed gas remaining in the gas piping with oxygen in the atmosphere can be reduced.

[0089] Furthermore, according to this embodiment, by performing the treatment by generating plasma in three stages, it becomes possible to obtain effects such as increasing the film formation rate by 50 to 100 times or more in the first stage, Plasma A, improving the etching resistance performance in the second stage, and improving the etching resistance performance and the actual pattern shape (reducing undercut) in the third stage, Plasma C.

[0090] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the above embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0091] 1: Plasma processing equipment 100: Vacuum container 101: substrate to be processed 102: Shower plate 103: Sample mounting table 104: Plasma generation power supply 105: Mass flow controller 106: Gas line 107: Exhaust pipe 108: Pressure control valve 109: Pump 111: Heater

Claims

1. a first step of supplying a gas containing silicon and a halogen element into a vacuum processing chamber and generating plasma, and forming a film using the generated plasma; a second step of removing halogen elements by plasma generated using a gas containing hydrogen elements after the first step; a third step of oxidizing or nitriding the film by plasma after the second step, A film forming method, characterized in that the time for the plasma treatment in the first step is a time specified based on a normalized film formation rate of the film and a normalized plasma etching rate of the film.

2. a first step of supplying a gas containing silicon and a halogen element into a vacuum processing chamber for a predetermined time, generating plasma, and forming a film using the generated plasma; a second step of removing halogen elements by plasma generated using a gas containing hydrogen elements after the first step; a third step of oxidizing or nitriding the film by plasma after the second step, A film forming method, characterized in that the time for the plasma treatment in the first step is a time specified based on a normalized film formation rate of the film and a normalized plasma etching rate of the film.

3. 3. The film forming method according to claim 1, A film forming method comprising repeating the first to third steps multiple times.

4. 3. The film forming method according to claim 1, A film forming method characterized in that the time in the plasma treatment of the first step is the time when the normalized film formation rate becomes 1 or more and the normalized plasma etching rate of the film becomes 1 or less.

5. 5. The film forming method according to claim 4, The film forming method is characterized in that the plasma treatment time in the first step is within a range of 1 to 3 seconds.

6. 6. The film forming method according to claim 5, a time period for the plasma treatment in the first step is equal to or shorter than a time period for the plasma treatment in the second step; A film forming method, wherein the time for the plasma treatment in the second step is equal to or shorter than the time for the plasma treatment in the third step.

7. 7. The film forming method according to claim 6, A film forming method, characterized in that the pressure in the plasma treatment in the first step and the pressure in the plasma treatment in the second step are equal to or lower than the pressure in the plasma treatment in the third step.

8. 3. The film forming method according to claim 1, The film forming method, wherein the product of the time for the plasma treatment in the third step and the pressure for the plasma treatment in the third step is 60 (sec·Pa) or more.

9. 8. The film forming method according to claim 7, The film forming method, wherein the product of the time for the plasma treatment in the third step and the pressure for the plasma treatment in the third step is 60 (sec·Pa) or more.

10. 10. The film forming method according to claim 9, The film forming method, wherein the gas containing silicon and halogen is tetrachlorosilane gas.

11. a first step of supplying a gas containing silicon and a halogen element into a vacuum processing chamber and generating plasma, and forming a film using the generated plasma; a second step of removing halogen elements by plasma generated using a gas containing hydrogen elements after the first step; a third step of oxidizing or nitriding the film by plasma after the second step; a fourth step of plasma etching the target film after the third step, a plasma processing method, wherein the time for the plasma processing in the first step is a time specified based on a normalized film formation rate of the film and a normalized plasma etching rate of the film;

12. a first step of supplying a gas containing silicon and a halogen element into a vacuum processing chamber for a predetermined time, generating plasma, and forming a film using the generated plasma; a second step of removing halogen elements by plasma generated using a gas containing hydrogen elements after the first step; a third step of oxidizing or nitriding the film by plasma after the second step; a fourth step of plasma etching the target film after the third step, a plasma processing method, wherein the time for the plasma processing in the first step is a time specified based on a normalized film formation rate of the film and a normalized plasma etching rate of the film;

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