JP2020063470A - Method of depositing titanium oxide film for patterning spacer, and pattern formation method - Google Patents

Abstract

To provide a method of depositing a titanium oxide film for a patterning spacer which has excellent etching resistance in low temperature deposition, and a pattern formation method.SOLUTION: A method of depositing a titanium oxide film for a patterning spacer includes the steps of preparing a treatment base plate to patterning, setting the temperature of the treatment base plate to below 200°C, and alternately supplying titanium halide gas and plasma of oxygen-containing gas to deposit a titanium oxide film, being a patterning spacer, onto the treatment base plate by plasma ALD.SELECTED DRAWING: Figure 8

Description

  The present disclosure relates to a method for forming a titanium oxide film for a patterning spacer and a pattern forming method.

  In a semiconductor device manufacturing process, a technique called multiple patterning is used in order to form a fine pattern below a resolution limit of a photolithography method. As the multiple patterning, a self-aligned double patterning (SADP), a self-aligning quadruple patterning (SAQP) which repeats this twice, or the like is used. In the SADP process, a core material is formed on the laminated film by a photolithography method, a spacer film is formed on the side wall of the core material, the core material is removed, and then the base film is etched using the spacer film as a mask. The material of the spacer film is determined according to the material of the base film, and a titanium oxide film may be used.

  The titanium oxide film used for such a fine patterning spacer is required to be formed with high uniformity and high step coverage, and plasma ALD (PE-ALD) is known as a technique capable of realizing such film formation. Has been. In forming such a titanium oxide film for a patterning spacer, an organometallic precursor such as tetrakis (dimethylamide) Ti (TDMAT) having good controllability and no fear of chlorine corrosion is used as a titanium precursor. (For example, nonpatent literature 1).

W.J.Maeng and H. Kim, Electrochemical and Solid-State Letters, 9 (6) G191-G194 (2006)

  The present disclosure provides a method and a pattern forming method for forming a titanium oxide film for a patterning spacer having excellent etching resistance in low temperature film formation.

  A method according to an aspect of the present disclosure is a method of forming a titanium oxide film for a patterning spacer, which includes a step of preparing a substrate to be patterned and a step of setting the temperature of the substrate to be less than 200 ° C. And a step of alternately supplying a titanium halide gas and a plasma of an oxygen-containing gas to the substrate to be processed to form a titanium oxide film serving as a patterning spacer on the substrate to be processed by plasma ALD.

  According to the present disclosure, there are provided a method for forming a titanium oxide film for a patterning spacer and a method for forming a pattern, which have excellent etching resistance in low temperature film formation.

6 is a flowchart showing SADP which is an example of a pattern forming method to which the method for manufacturing a TiO ₂ film for a patterning spacer according to one embodiment is applied. FIG. 3 is a process sectional view showing step 1 of SADP that is an example of the pattern forming method shown in FIG. 1. FIG. 6 is a process sectional view showing step 2 of SADP, which is an example of the pattern forming method shown in FIG. 1. FIG. 6 is a process sectional view showing step 3 of SADP, which is an example of the pattern forming method shown in FIG. 1. FIG. 6 is a process sectional view showing step 4 of SADP, which is an example of the pattern forming method shown in FIG. 1. FIG. 9 is a process sectional view showing step 5 of SADP, which is an example of the pattern forming method shown in FIG. 1. FIG. 6 is a process sectional view showing step 6 of SADP, which is an example of the pattern forming method shown in FIG. 1. 6 is a flowchart showing a method of forming a TiO ₂ film for a patterning spacer according to one embodiment. Is a sectional view showing an example of a suitable film-forming apparatus to the deposition of the TiO ₂ film for patterning spacer. 10 is a timing chart showing a film forming sequence when forming a TiO ₂ film in the film forming apparatus of FIG. 9. Is a diagram showing the relationship between the deposition temperature and WER when the as titanium precursor with TiCl ₄ was deposited TiO ₂ film with a case and TDMAT depositing the TiO ₂ film. It is a GPC values and the variation with respect to the plasma irradiation time in case of forming the TiO ₂ film using TiCl ₄ as a titanium precursor (1 [sigma). It is a GPC values and the variation (1 [sigma) for the plasma irradiation time in case of forming the TiO ₂ film using TDMAT as the titanium precursor.

  Embodiments will be described below with reference to the accompanying drawings.

<Background and overview>
First, the history and outline of the method for forming a titanium oxide film for a patterning spacer according to the embodiment of the present disclosure will be described.
Conventionally, plasma ALD has been used as a titanium oxide (TiO ₂ ) film for patterning spacers. As a titanium precursor used at that time, an organic metal precursor such as TDMAT described in Non-Patent Document 1 is used. Was limited to. This is because titanium tetrachloride (TiCl ₄ ) has poor controllability during film formation, and there is concern about chlorine corrosion.

By the way, in the multiple patterning process, a material having low heat resistance such as a photoresist film or a spin coat film is often used as a film used for patterning. Further, the TiO ₂ film is crystallized at a film forming temperature of 200 ° C. or higher, and if crystallized, it becomes difficult to form a film with high accuracy. Therefore, the film formation temperature of the TiO ₂ film for the patterning spacer is required to be as low as less than 200 ° C., and recently, the film formation temperature is required to be 140 ° C. or lower, and further 120 ° C.

  However, when a low temperature film formation is performed using an organometallic precursor as the titanium precursor, the film quality is deteriorated and there is a problem that the etching resistance such as resistance to wet etching performed during patterning (wet etching resistance) is low. It has been found.

It has been found that the cause of such deterioration of film quality is that carbon (C) and nitrogen (N) contained in the organometallic precursor are taken into the film as impurities in the case of low-temperature film formation. That is, in the TiO ₂ film, Ti and O are strongly bonded to form a network, but if C or N is taken into the film as an impurity, the formation of the network is hindered and the etching resistance is lowered.

Therefore, as a result of studies by the inventors, by using a titanium halide gas such as TiCl ₄ gas as the titanium precursor, the deterioration of the film quality due to the incorporation of C and N into the film is suppressed even in the low temperature film formation, It has been found that a high etching resistance can be maintained.

  Further, even if the precursor contains halogen such as Cl, the problem of controllability at the time of film formation can be solved by the provision of manufacturing conditions, etc., and halogen (Cl) corrosion can be solved by a countermeasure on the device side. did.

Therefore, in one aspect, in forming the TiO ₂ film for the patterning spacer, a step of preparing a substrate to be patterned, a step of setting the temperature of the substrate to be less than 200 ° C., a titanium halide gas and oxygen. A step of forming a TiO ₂ film to serve as a patterning spacer by performing plasma ALD by alternately supplying plasma of a containing gas to the substrate to be processed is performed.

<Pattern forming method in which a TiO ₂ film is applied as a patterning spacer>
Next, an example of a pattern forming method to which the method for manufacturing a TiO ₂ film for a patterning spacer according to one embodiment is applied will be described. Here, SADP in the case of using a TiO ₂ film as the patterning spacer will be described.

  FIG. 1 is a flow chart showing the SADP of this example, and FIGS. 2 to 7 are process cross-sectional views showing the respective processes at that time.

  First, as a substrate to be processed, for example, a semiconductor wafer in which an etching target film 202 is formed on a semiconductor substrate 201 typified by silicon and a core material 203 having a predetermined pattern is formed thereon (hereinafter, simply referred to as a wafer Prepare W (step 1, FIG. 2).

  The core material 203 is formed in a predetermined pattern on a predetermined film by photolithography and etching.

  The wafer W, which is the substrate to be processed, actually has a plurality of films, and pattern formation is performed while transferring the patterns by sequentially etching the plurality of films, but here, for simplification of description, The case where one layer of the etching target film 202 is formed is shown.

Next, a TiO ₂ film 204 for patterning spacers is formed on the surface of the wafer W on which the core material 203 is formed (step 2, FIG. 3). Details of the method for forming the TiO ₂ film 204 will be described later.

Next, the TiO ₂ film 204 is dry-etched to form spacers 205 on both side walls of the core material 203 (step 3, FIG. 4).

  Next, the core material 203 is removed by wet etching to form a pattern of the spacer 205 having a pattern width half that of the core material 203 (step 4, FIG. 5).

  Next, the lower-layer etching target film 202 is anisotropically etched using the spacer 205 as an etching mask (step 5, FIG. 6). As a result, an etching pattern 206 having a pattern width half that of the core material 203 is formed on the etching target film 202.

  Next, the remaining spacer 205 is removed by etching (step 6, FIG. 7).

In this way, when forming a pattern by SADP, since the core material 203 is removed by wet etching, the spacer made of the TiO ₂ film is required to have high etching resistance.

<Method for forming titanium oxide film for patterning spacer>
Next, a specific embodiment of the method for forming the TiO ₂ film for the patterning spacer will be described. FIG. 8 is a flowchart showing a method of forming a TiO ₂ film for a patterning spacer according to one embodiment.

  First, a substrate to be patterned is prepared (step 11). Specifically, the substrate to be processed is provided in the chamber of the film forming apparatus. As the substrate to be processed, for example, a wafer W as shown in FIG. 2 is used.

  Next, the temperature of the substrate to be processed is set to less than 200 ° C. (step 12). This is because at temperatures above 200 ° C., the titanium oxide film crystallizes, the irregularities of the crystal grain boundaries are transferred to the underlying layer, and it is difficult to obtain a highly accurate pattern, and many films used for multiple patterning have low heat resistance. It is because it has become. From these viewpoints, it is preferable that the temperature is further lower, preferably 140 ° C. or lower, further preferably 120 ° C. or lower.

Next, a titanium halide gas and a plasma of an oxygen-containing gas are alternately supplied to the substrate to be processed to form a TiO ₂ film to be a patterning spacer on the substrate to be processed by plasma ALD (step 13).

That is, the titanium halide gas and the plasma of the oxygen-containing gas are alternately present in the chamber while sandwiching the purge in the chamber. As a specific example, a purge gas for purging the inside of the chamber and an oxygen-containing gas are continuously supplied into the chamber, while the titanium halide gas is supplied to the chamber and the plasma of the oxygen-containing gas is generated. Is repeated intermittently. As a result, the titanium halide gas supply → purging in the chamber → plasma generation of the oxygen-containing gas → purging in the chamber is repeated, and the TiO ₂ film is formed by plasma ALD.

  The oxygen-containing gas may be supplied only when plasma is generated. Further, purging in the chamber may be performed only by vacuuming.

As a typical titanium halide gas, TiCl ₄ gas can be mentioned. Titanium tetrabromide (TiBr ₄ ) gas and titanium tetraiodide (TiI ₄ ) gas can also be used as the titanium halide gas.

As the oxygen-containing gas, oxygen gas (O ₂ gas) can be preferably used, but other oxygen-containing gas such as ozone gas can also be used. The oxygen-containing gas plasma is formed to generate oxygen radicals that contribute to the oxidation. The plasma is not particularly limited, and various types of plasma such as capacitively coupled plasma (parallel plate type), inductively coupled plasma, and microwave plasma can be applied. Of these, capacitively coupled plasma is preferable because it has good plasma responsiveness during plasma ALD. Further, when using the capacitively coupled plasma, it is preferable to use a condition that results in low ion energy.

An inert gas can be used as the purge gas. Examples of the inert gas include rare gases such as Ar gas and N ₂ gas.

  The pressure in the chamber is preferably in the range of 66.5 to 1330 Pa (0.5 to 10 Torr). The supply time of titanium halide per time is preferably in the range of 0.03 to 2 sec. The irradiation time of the oxygen-containing plasma per time is preferably in the range of 0.1 to 2 sec.

In the present embodiment, good etching resistance can be obtained by using the titanium halide gas as the titanium precursor when forming the patterning spacer TiO ₂ film by plasma ALD at a low temperature of less than 200 ° C. .

  When a conventional organometallic precursor such as TDMAT is used as the titanium precursor, when a film is formed at a low temperature, impurities such as C and N are taken into the film, and the etching resistance is lowered. On the other hand, by using a titanium halide gas as the titanium precursor, C, N, etc. are not taken into the film, so that good etching resistance can be maintained even at low temperatures. Further, conventionally, there has been concern about controllability during film formation, halogen (Cl) corrosion, and the like due to inclusion of halogen such as Cl in the titanium precursor. However, it was found that the controllability problem can be solved by the countermeasures on the equipment side, because the halogen corrosion can be solved by the regulation of manufacturing conditions.

Further, by using a titanium halide such as TiCl ₄ as the titanium precursor, it is more robust against the plasma irradiation time than using an organic titanium precursor such as TDMAT. That is, even if the plasma irradiation time changes, the change in the film formation rate (GPC) is small.

<TiO ₂ film forming apparatus>
Next, an example of a film forming apparatus suitable for forming a TiO ₂ film for a patterning spacer will be described. FIG. 9 is a sectional view showing an example of such a film forming apparatus.

  As shown in FIG. 9, the film forming apparatus 100 includes a chamber 1, a susceptor 2, a shower head 3, an exhaust unit 4, a gas supply mechanism 5, a plasma generation mechanism 6, and a control unit 7. ing.

  The chamber 1 is made of a metal such as aluminum and has a substantially cylindrical shape. A loading / unloading port 11 for loading / unloading the wafer W is formed on a sidewall of the chamber 1, and the loading / unloading port 11 can be opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the chamber 1. The exhaust duct 13 has a slit 13a formed along the inner peripheral surface thereof. An exhaust port 13b is formed on the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the chamber 1. An insulating ring 16 is fitted on the outer periphery of the ceiling wall 14, and a seal ring 15 hermetically seals between the insulating ring 16 and the exhaust duct 13.

  The susceptor 2 is for horizontally supporting the wafer W, which is a substrate to be processed, in the chamber 1. The susceptor 2 has a disk shape having a size corresponding to the wafer W, and is supported by the support member 23. The susceptor 2 is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as aluminum or a nickel-based alloy, and has a heater 21 embedded therein for heating the wafer W. The heater 21 is adapted to generate heat by being supplied with power from a heater power supply (not shown). Then, the output of the heater 21 is controlled by the temperature signal of a thermocouple (not shown) provided in the vicinity of the wafer mounting surface on the upper surface of the susceptor 2, so that the wafer W is controlled to a predetermined temperature. There is.

  The susceptor 2 is provided with a cover member 22 made of ceramics such as alumina so as to cover the outer peripheral region of the wafer mounting surface and the side surface of the susceptor 2.

  The support member 23 that supports the susceptor 2 extends from the center of the bottom surface of the susceptor 2 through the hole formed in the bottom wall of the chamber 1 to the lower side of the chamber 1, and the lower end thereof is connected to the lifting mechanism 24. The lifting mechanism 24 allows the susceptor 2 to be lifted via the support member 23 between a processing position shown in FIG. 9 and a transfer position below which a wafer can be transferred indicated by a chain line. Further, a collar member 25 is attached to a position below the chamber 1 of the support member 23, and an atmosphere in the chamber 1 is separated from outside air between the bottom surface of the chamber 1 and the collar member 25, so that the susceptor 2 has a structure. A bellows 26 is provided that expands and contracts as it moves up and down.

  Three wafer support pins 27 (only two are shown) are provided near the bottom surface of the chamber 1 so as to project upward from the elevating plate 27a. The wafer support pin 27 can be moved up and down via an elevating plate 27a by an elevating mechanism 28 provided below the chamber 1, and is inserted into a through hole 2a provided in the susceptor 2 at the transfer position to be inserted into the susceptor 2. Can be sunk into the upper surface of the. By raising and lowering the wafer support pins 27 in this manner, the wafer W is transferred between the wafer transfer mechanism (not shown) and the susceptor 2.

  The shower head 3 is a metal member for supplying the processing gas into the chamber 1 in a shower shape, is provided so as to face the susceptor 2, and has a diameter substantially the same as that of the susceptor 2. The shower head 3 has a main body portion 31 fixed to the ceiling wall 14 of the chamber 1, and a shower plate 32 connected below the main body portion 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32, and the gas diffusion space 33 is provided so as to penetrate the main body 31 and the center of the ceiling wall 14 of the chamber 1. The gas introduction hole 36 is connected. An annular protrusion 34 that protrudes downward is formed on the peripheral edge of the shower plate 32, and a gas discharge hole 35 is formed on a flat surface inside the annular protrusion 34 of the shower plate 32.

  When the susceptor 2 is in the processing position, a processing space 37 is formed between the shower plate 32 and the susceptor 2, and the annular protrusion 34 and the upper surface of the cover member 22 of the susceptor 2 are close to each other to form an annular gap 38. To be done.

  The exhaust unit 4 is for exhausting the inside of the chamber 1, and includes an exhaust pipe 41 connected to the exhaust port 13b of the exhaust duct 13 and a vacuum pump, a pressure control valve, etc. connected to the exhaust pipe 41. And an exhaust mechanism 42 included therein. During processing, the gas in the chamber 1 reaches the exhaust duct 13 through the slit 13a, and is exhausted from the exhaust duct 13 by the exhaust mechanism 42 of the exhaust unit 4 through the exhaust pipe 41.

The gas supply mechanism 5 is for supplying gas to the shower head 3, and includes a TiCl ₄ gas supply source 51, an O ₂ gas supply source 52, a first Ar gas supply source 53, and a second Ar gas supply source 54. Have and. The TiCl ₄ gas supply source 51 supplies TiCl ₄ gas as titanium halide gas. The O ₂ gas supply source 52 supplies O ₂ gas as an oxygen-containing gas. The first Ar gas supply source 53 and the second Ar gas supply source 54 gas supply Ar gas that functions as a carrier gas, a purge gas, a plasma generating gas, and the like. The gas supply mechanism 5 further includes a TiCl ₄ gas supply pipe 61, an O ₂ gas supply pipe 62, a first Ar gas supply pipe 63, and a second Ar gas supply pipe 64. The TiCl ₄ gas supply pipe 61 extends from the TiCl ₄ gas supply source 51, the O ₂ gas supply pipe 62 extends from the O ₂ gas supply source 52, the first Ar gas supply pipe 63 extends from the first Ar supply source 53, and the second Ar gas The supply pipe 64 extends from the second Ar gas supply source 54.

The TiCl ₄ gas supply pipe 61 and the O ₂ gas supply pipe 62 join a joining pipe 66, and the joining pipe 66 is connected to the gas introduction hole 36 described above. The first Ar gas supply pipe 63 is connected to the TiCl ₄ gas supply pipe 61, and the second Ar gas supply pipe 64 is connected to the O ₂ gas supply pipe 62. The TiCl ₄ gas supply pipe 61 is provided with a mass flow controller 71a, which is a flow rate controller, and an opening / closing valve 71b. The O ₂ gas supply pipe 62 is provided with a mass flow controller 72a and an opening / closing valve 72b, the first Ar gas supply pipe 63 is provided with a mass flow controller 73a and an opening / closing valve 73b, and the second Ar gas supply pipe 64 is provided. A mass flow controller 74a and an opening / closing valve 74b are provided.

  Then, by switching the open / close valves 71b, 72b, 73b, 74b, a desired ALD process as described later can be performed.

The Ar gas flow rate may be increased during the purging step by branching from the first Ar gas supply piping 63 and the second Ar gas supply piping 64 to provide piping for increasing the Ar gas flow rate only during purging. Further, the purge gas or the like is not limited to Ar gas, but may be other inert gas such as N ₂ gas or a rare gas other than Ar.

  The plasma generation mechanism 6 has a power supply line 81 connected to the main body 31 of the shower head 3, a matching unit 82 and a high frequency power supply 83 connected to the power supply line 81, and an electrode 84 embedded in the susceptor 2. ing. By supplying high frequency power to the shower head 3 from the high frequency power supply 81, a high frequency electric field is formed between the shower head 3 and the electrode 84, and the high frequency electric field generates plasma of a predetermined processing gas. The frequency of the high frequency power source 83 is preferably set to 450 kHz to 220 MHz, and for example, 450 kHz is used.

  The control unit 7 includes a main control unit including a computer (CPU) for controlling each component of the film forming apparatus, for example, a valve, a mass flow controller, a power supply, a heater, a vacuum pump, an input device, an output device, a display device, And a storage device. The storage device stores parameters of various processes executed by the film forming apparatus 100. Further, the storage device has a storage medium in which a program for controlling the processing executed in the film forming apparatus 100, that is, a processing recipe is stored. The main control unit calls a predetermined processing recipe stored in the storage medium, and causes the film forming apparatus 100 to perform a predetermined operation based on the processing recipe.

  In the film forming apparatus 100 configured as described above, first, the gate valve 12 is opened, and the wafer W is loaded into the chamber 1 through the loading / unloading port 11 by the transporting device (not shown), and is loaded onto the susceptor 2. Place it. The transport device is retracted, and the susceptor 2 is raised to the processing position. Then, the gate valve 12 is closed, the inside of the chamber 1 is maintained at a predetermined depressurized state, and the heater 21 controls the temperature of the susceptor 2 to a predetermined temperature.

In this state, the switch valve 73b, opened 74b and 75b, _{O 2} gas _{O 2} gas supply source 52, continuously supplying the Ar gas from the 1Ar gas supply source 53 and the 2Ar gas supply source 54. While supplying these, by intermittently opening and closing the on-off valve 71b of the TiCl ₄ gas supply pipe 61 and turning on and off the high frequency power source 83, as shown in FIG. 10, Ar gas + O ₂ gas + TiCl ₄ gas Supply period (T1), Ar gas + O ₂ gas supply period (T2), O ₂ gas plasma generation period (T3), and Ar gas + O ₂ gas supply period (T4) are sequentially repeated. As a result, the cycle of supply of TiCl ₄ gas → purging in the chamber → generation of O ₂ plasma → purging in the chamber is repeated to form a TiO ₂ film by plasma ALD. The purge period (T4) after the supply of the O ₂ plasma at T3 may be short.

After the two-stage TiO ₂ film is formed in this way, the chamber 1 is purged, the susceptor 2 is lowered, the gate valve 12 is opened, and the wafer W is unloaded.

Examples of the processing condition at this time include the following conditions.
Pressure: 66.5 to 1330 Pa (0.5 to 10 Torr)
Temperature: less than 200 ° C (preferably 140 ° C or less, more preferably 120 ° C or less)
TiCl ₄ gas flow rate: 100 to 1000 sccm
O ₂ gas flow rate: 1000 to 10000 sccm
High frequency power: 50-1000W
Ar gas flow rate: 1000 to 10000 sccm
T1 time: 0.03 to 2 sec
T3 time: 0.1-10 sec
T2 time: 0.1-2 sec
T4 time: 0-10 sec

In the above example, the O ₂ gas was continuously supplied, but the O ₂ gas may be supplied only during the plasma generation period (T3) of the O ₂ gas.

<Experimental example>
Next, an experimental example will be described.

[Experimental Example 1]
Here, TiCl ₄ gas was used as the titanium precursor and O ₂ gas was used as the oxygen-containing gas, and a TiO ₂ film was formed by plasma ALD using the film forming apparatus shown in FIG. A high frequency power source having a frequency of 450 kHz was used and a power 3 was set to 300 W. The pressure in the chamber was set to 266 Pa (2 Torr). Then, the times of T1, T2, T3, and T4 described above are set to 0.05 sec, 1.2 sec, 0.4 sec, and 0.1 sec, respectively, and the film formation temperature is changed between 60 and 120 ° C. to change the TiO ₂ film. Was deposited. The formed TiO ₂ was subjected to wet etching with hydrofluoric acid, and the etching resistance (wet etching resistance) at that time was obtained. The wet etching resistance was grasped by obtaining the etching rate (WER) when performing wet etching. That is, the lower the WER, the higher the etching resistance (wet etching resistance). For comparison, the same conditions as those using TiCl ₄ gas except that TDMAT gas, which is an organic titanium precursor, was used as the titanium precursor, T1 time was 0.4 sec, and T3 time was 0.2 sec. Then, a TiO ₂ film was formed, and wet etching resistance was similarly obtained. The result is shown in FIG.

As shown in FIG. 11, it was confirmed that the etching resistance was higher when TiCl ₄ gas was used as the titanium precursor than when TDMAT gas was used at a low film forming temperature of 120 ° C. or lower. It was also confirmed that the lower the film forming temperature, the greater the difference in etching resistance.

[Experimental Example 2]
Here, as in Experimental Example 1, a TiCl ₄ gas was used as a titanium precursor, and an O ₂ gas was used as an oxygen-containing gas to form a TiO 2 film by plasma ALD. The frequency power and pressure of the high frequency power source were the same as in Experimental Example 1, and the film forming temperature was 100 ° C. Further, the times of T1, T2, and T4 described above were set to 0.05 sec, 1.2 sec, and 0.1 sec, respectively, and the plasma irradiation time T3 was changed in the range of 0.4 to 1.0 sec. Then, the film formation amount (GPC) of the TiO ₂ film per cycle in each plasma irradiation time was obtained. FIG. 12 shows the GPC value and its variation (1σ) with respect to the plasma irradiation time at that time.

Further, for comparison, TDMAT gas, which is an organic titanium precursor, was used as the titanium precursor, the plasma irradiation time T3 was changed to form a TiO ₂ film, and the GPC at each plasma irradiation time was obtained. At this time, the same conditions as in the case of using TiCl ₄ gas were used except that the time T1 was 0.4 sec and the time T3 was changed between 0.2 and 1.2 sec. FIG. 13 shows the GPC value and its variation (1σ) with respect to the plasma irradiation time at that time.

By comparing FIG. 12 and FIG. 13, it was confirmed that the change in GPC with respect to the plasma irradiation time was smaller when TiCl ₄ gas was used as the titanium precursor than when TDMAT gas was used.

<Other applications>
Although the embodiments have been described above, it should be considered that the embodiments disclosed this time are examples in all points and not restrictive. The above-described embodiments may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.

  For example, the film forming apparatus is merely an example, and is not particularly limited as long as it is a film forming apparatus using plasma. For example, the plasma generation method is also arbitrary, and not limited to a single-wafer type apparatus, a batch type apparatus or a semi-batch type apparatus that processes a plurality of substrates at once may be used.

1; chamber 2; susceptor 3; shower head 4; exhaust unit 5; gas supply mechanism 6; plasma generation mechanism 7; control unit 100; film forming apparatus 201; semiconductor substrate 202; etching target film 203; core material 204; patterning spacer TiO ₂ film 205; spacer 206; etching pattern

Claims (15)

A method for forming a titanium oxide film for a patterning spacer, comprising:
A step of preparing a substrate to be patterned,
A step of setting the temperature of the substrate to be processed to less than 200 ° C.,
A step of alternately supplying a titanium halide gas and a plasma of an oxygen-containing gas to the substrate to be processed to form a titanium oxide film serving as a patterning spacer on the substrate to be processed by plasma ALD;
Having a method.   The method according to claim 1, wherein the temperature of the substrate to be processed is 140 ° C. or lower.   The method according to claim 2, wherein the temperature of the substrate to be processed is 120 ° C. or lower. The method according to any one of claims 1 to 3, wherein the titanium halide gas is TiCl ₄ gas.   The method according to any one of claims 1 to 4, wherein the oxygen-containing gas is oxygen gas. In the step of preparing the substrate to be patterned, the substrate to be processed is placed in a chamber of a film forming apparatus,
In the step of forming a titanium oxide film to be the patterning spacer, the titanium halide gas and plasma of the oxygen-containing gas are alternately supplied into the chamber with a purge in the chamber sandwiched therebetween. The method according to any one of claims 1 to 5.   The method according to any one of claims 1 to 6, wherein the plasma of the oxygen-containing gas is capacitively coupled plasma.   The method according to claim 7, wherein the frequency of the high frequency power used to generate the capacitively coupled plasma is 450 kHz to 220 MHz. A step of forming a film to be etched on a semiconductor substrate, and further preparing a substrate to be processed having a core material of a predetermined pattern on the film to be etched;
A step of forming a titanium oxide film for patterning spacers on the surface of the substrate to be processed on which the core material is formed,
Dry etching the titanium oxide film to form spacers on both sidewalls of the core,
Removing the core material by wet etching to form the spacer pattern,
Anisotropically etching the etching target film using the spacer as an etching mask;
Have
In the step of forming the titanium oxide film for patterning spacers, the temperature of the substrate to be processed is lower than 200 ° C., titanium halide gas and plasma of oxygen-containing gas are alternately supplied to the substrate to be processed, and plasma ALD is performed. A pattern forming method, wherein a titanium oxide film to be a patterning spacer is formed on the substrate to be processed.   The pattern forming method according to claim 9, wherein in the step of forming the titanium oxide film for patterning spacers, the temperature of the substrate to be processed is 140 ° C. or lower.   The pattern forming method according to claim 10, wherein in the step of forming the titanium oxide film for patterning spacers, the temperature of the substrate to be processed is 120 ° C. or lower. The pattern forming method according to any one of claims 9 to 11, wherein the titanium halide gas is TiCl ₄ gas.   The pattern forming method according to any one of claims 9 to 12, wherein the oxygen-containing gas is oxygen gas.   The pattern forming method according to claim 9, wherein the plasma of the oxygen-containing gas is capacitively coupled plasma.   15. The pattern forming method according to claim 14, wherein the frequency of the high frequency power used to generate the capacitively coupled plasma is 450 kHz to 220 MHz.

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