TWI820170B - Plasma processing method and plasma processing apparatus - Google Patents

Abstract

A plasma processing method executed by a plasma processing apparatus in the present disclosure includes a first step and a second step. In the first step, the plasma processing apparatus forms a first film on the side walls of an opening in the processing target, the first film having different thicknesses along a spacing between pairs of side walls facing each other. In the second step, the plasma processing apparatus forms a second film by performing a film forming cycle once or more times after the first step, the second film having different thicknesses along the spacing between the pairs of side walls facing each other.

Description

Plasma treatment method and plasma treatment device

The following disclosure relates to plasma treatment methods and plasma treatment apparatuses.

As a means of forming a film on a substrate, the plasma enhanced atomic layer deposition (PE-ALD) method is widely known. We apply various technologies including the PE-ALD method to the patterning of semiconductor devices.

For example, we propose a method using ALD (Atomic Layer Deposition) to selectively promote film formation depending on the position of the opening formed in the substrate to be processed (Patent Document 1). Furthermore, we have proposed a method of selectively forming a SAM (Self-assembled monolayer) and then performing vapor phase etching (Patent Document 2). Furthermore, we have proposed a method to achieve selective film formation of 3D nanostructures using ion implantation (Non-Patent Document 1).

[Prior Technical Document] 〔Patent documents〕

Patent Document 1: U.S. Patent Application Publication No. 2017/0140983

Patent Document 2: Specification of U.S. Patent Application Publication No. 2017/0148642

[Non-patent literature]

Non-patent document 1: Woo-Hee Kim et al., "A Process for Topographically Selective Deposition on 3D Nanostructures by Ion Implantation" ACS Nano 2016, 10, 4451-4458.

This specification provides a technology that can achieve precise dimensional control of patterns formed on a substrate.

A plasma processing method performed by a plasma processing device according to this specification includes a first process and a second process. In the first process, the plasma processing device forms a first film whose thickness varies depending on the distance between the pair of opposing side walls on the side walls of the opening of the treatment object. In the second process after the first process, the plasma treatment device performs the film forming cycle more than once to form a second film with a thickness that varies depending on the distance between the opposite pairs of side walls.

According to this specification, precise dimensional control of the pattern formed on the substrate can be achieved.

10: Plasma treatment device

21: Chamber

22:Insulation board

23:Support Desk

24: base

25:Electrostatic chuck

25a: Focus ring

26:Electrode

27:DC power supply

28:Inner wall components

29:Refrigerant room

30a, 30b: Piping

31:Piping

33: Matcher

34:RF power supply

36a, 36b: Pressure gauge

37a, 37b: valve

38, 38a, 38b: piping

40: Upper electrode

41:Roof support part

42:Top plate

42a:Gas inlet

43: Diffusion chamber

43a: Circulation port

45:Insulating components

46:Gas inlet

47:Piping

48a~48c: Gas supply source

49a~49c: Mass flow controller (MFC)

50a~50c: valve

51: Matcher

52:RF power supply

60:Control device

61:Memory

62: Processor

63:User interface

71:Exhaust port

72:Exhaust pipe

73:Exhaust device

74:Open your mouth

76, 77: Deposition barrier

78:Open your mouth

79:GND block

G: Gate valve

O1~O7: opening

W:wafer

S61~S65: steps

FIG. 1 shows an example of the structure of a plasma processing apparatus according to an embodiment.

Figure 2A is used to illustrate the chemical adsorption step of precursor gas in ALD.

Figure 2B illustrates the scrubbing step of precursor gas in ALD.

Figure 2C is used to illustrate the activation step caused by the reactive gas in ALD.

Figure 2D is used to illustrate the gas scrubbing step of the reaction gas in ALD.

FIG. 3A is a diagram (1) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 3B is a diagram (2) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 3C is a diagram (3) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 3D is a diagram (4) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 3E is a diagram (5) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 3F is a diagram (6) for explaining the latency in the plasma treatment method according to one embodiment.

FIG. 4A is used to illustrate the size control of the opening formed in the mask.

FIG. 4B illustrates an example of the opening formed in the mask.

FIG. 4C shows an example of a pattern formed when etching is performed using the mask of FIG. 4B .

Figure 5A illustrates the X-Y pattern.

Figure 5B is used to illustrate the size control example 1 of the X-Y pattern.

Figure 5C is used to illustrate the size control example 2 of the X-Y pattern.

FIG. 6 is an example of a general flowchart of a plasma treatment method in a plasma treatment apparatus according to an embodiment. Display the flow chart.

Figure 7 is used to illustrate an example of the loading effect.

FIG. 8A is a diagram (1) illustrating the X>Y shrinkage effect obtained by a plasma treatment method according to an embodiment.

FIG. 8B is a diagram (2) illustrating the X>Y shrinkage effect obtained by the plasma treatment method of an embodiment.

FIG. 9 shows a combination example of materials to be processed to which the plasma processing method according to one embodiment is applied.

FIG. 10A is used to illustrate the first procedure of the plasma treatment method in Modification 2.

FIG. 10B is used to illustrate the second procedure of the plasma treatment method in Modification 2.

[Better form of implementing the invention]

Hereinafter, the disclosed embodiment will be described in detail based on the drawings. In addition, this embodiment is not limiting. Moreover, each embodiment can be combined appropriately within the range which does not conflict with the processing content.

<The latent mechanism in ALD>

Before describing the implementation form, the underlying mechanism in ALD will be explained first.

Figures 2A to 2D illustrate an example of a general ALD process. Figure 2A is used to illustrate the chemical adsorption step of precursor gas in ALD. Figure 2B illustrates the scrubbing step of precursor gas in ALD. Figure 2C To illustrate the activation step caused by the reactive gas in ALD. Figure 2D is used to illustrate the gas scrubbing step of the reaction gas in ALD. ALD, as shown in Figures 2A to 2D, generally includes the following four steps.

(1) In the chemical adsorption step, the processing object (such as a semiconductor substrate) placed in the processing chamber is exposed to the precursor gas (see Figure 2A)

(2) Gas scrubbing step, scrubbing the precursor gas remaining in the treatment chamber (see Figure 2B)

(3) Reaction step, exposing the treatment object placed in the treatment chamber to the reaction gas (see Figure 2C)

(4) Gas scrubbing step: scrubbing the reaction gas remaining in the treatment chamber (see Figure 2D)

In addition, in the following description, the reaction step (3) is performed by plasmaizing the reaction gas. In ALD, the above steps (1) to (4) are repeated to form a film on the processing object. In addition, gas scrubbing steps (2) and (4) are arbitrary steps and may not necessarily be performed.

In ALD, for example, a silicon-containing gas is used as a precursor gas and an O-containing gas is used as a reactive gas to deposit a SiO ₂ film on the processing object. In this case, in the first step (1), the processing object placed in the processing chamber is exposed to the precursor gas, that is, the silicon-containing gas. In this way, the silicon-containing gas is chemically adsorbed on the surface of the treatment object. The precursor gas that is not chemically adsorbed on the processing object but remains in the processing chamber is scrubbed in step (2). Thereafter, in step (3), the O-containing gas is plasmatized, and the oxygen radicals react with the silicon-containing molecules chemically adsorbed on the treatment object (silicon oxidation) to form a layer of SiO ₂ film. The O-containing gas remaining in the treatment chamber is scrubbed in step (4). ALD basically forms a film layer by layer. If there is no surface on the treatment object to which atoms are chemically adsorbed, the process will stop, so it can form a self-limiting conformal film.

However, factors that hinder the chemical adsorption of the precursor gas (hereinafter also referred to as inhibitors) If it exists on the surface of the processing object, the precursor gas will not be chemically adsorbed on the processing object in step (1), and film formation by ALD will not be performed. The delay in the start of film formation due to such hindering factors is called latency. 3A to 3F are diagrams (1) to (6) used to explain a plasma treatment method according to an embodiment.

FIG. 3A shows a state in which a CF film is formed on the surface of a treatment object using chemical vapor deposition (CVD) of CF (fluorocarbon) or the like. In FIG. 3A , fluorine atoms (CF: fluorine atoms covalently bonded to carbon) are represented by black circles. In addition, atoms of the processing target (substrate) are represented by white circles.

FIG. 3B shows an example of a state in which the ALD cycle is executed once for the processing object shown in FIG. 3A . Since there is a CF film, which is an inhibitor, on the surface of the treatment object, the precursor gas (silicon-containing gas) is not chemically adsorbed, and film formation by ALD is not performed. On the contrary, the CF film is gradually removed from the surface of the treated object due to the influence of oxygen radicals generated by utilizing oxygen plasma in the ALD cycle.

FIG. 3C shows an example of a state in which the ALD loop is executed five times for the processing object shown in FIG. 3A . In the example of Figure 3C, the entire CF film has been removed through 5 ALD cycles.

FIG. 3D , FIG. 3E , and FIG. 3F each show an example of a state in which the ALD loop is executed 6 times, 8 times, and 10 times for the processing target shown in FIG. 3A . As shown in FIG. 3C , the CF film is removed by performing the ALD cycle five times, and the layer under the CF film is exposed. In this state, there are substances on the surface of the treatment object that the precursor gas can chemically adsorb. Therefore, the precursor gas chemically adsorbs and reacts with the reactive gas, and as shown in Figure 3D, film formation begins. Thereafter, as shown in Figures 3E and 3F, the film thickness increases each time the ALD cycle is executed. In FIGS. 3D, 3E, and 3F, the circle in the second layer from the top represents the Si-containing precursor gas, and the uppermost circle represents oxygen atoms.

<Control of X-Y pattern>

However, during manufacturing of semiconductor devices, various patterns are formed on the substrate. For example, a plurality of openings having the same shape may be formed on one substrate. In this case, precise control of the size of the opening affects the performance of the semiconductor device.

FIG. 4A is used to illustrate the size control of the opening formed in the mask. The substrate S shown in FIG. 4A is formed by self-aligned double patterning. Therefore, on the surface of the substrate S, lines formed by different types of material A (core), material B (spacer), and material C (filler) are arranged according to A, B, C, B, A, B, C, B, A in the order. Hereinafter, the line formed of material A is called line A, the line formed of material B is called line B, and the line formed of material C is called line C. Here, we consider using a mask with a shape represented by a dotted line in FIG. 4A to perform etching of the substrate S. Figure 4A shows: openings O1, O2, O4, O5, O6, O7, which are formed as two ends respectively located on mutually different lines C; and opening O3, which is formed as two ends respectively. On line A that are different from each other. In addition, for the convenience of explanation, the long side direction of the lines shown in FIGS. 4A to 4C is called the X1 direction, and the direction transverse to the lines is called the Y1 direction.

In the case where a mask having a shape as shown in FIG. 4A is formed, there is no big problem with the shape of the pattern subsequently formed by etching. However, as shown in FIG. 4B , the opening of the mask is formed at a position shifted in the Y1 direction from the desired position. FIG. 4B illustrates an example of the opening formed in the mask. This feeling Under this situation, when using this mask to perform etching of the substrate S, there is the following possibility: as shown in FIG. 4C, the position of the opening formed on the substrate S is shifted further in the Y1 direction and is not formed into the Line C is connected. FIG. 4C shows an example of a pattern formed when etching is performed using the mask of FIG. 4B . When a mask is formed as shown in FIG. 4B , in order to prevent the malfunction shown in FIG. 4C from occurring, it would be convenient if the size of the opening of the mask formed in the process can be adjusted. In particular, in the case of a mask having a shape as shown in FIG. 4A , compared with the size control in the short-side direction of the opening, the size control in the long-side direction affects the subsequent wiring formation more. As mentioned above, a substantially rectangular opening having a short side and a long side in plan view may be called an X-Y pattern.

Figure 5A illustrates the X-Y pattern. Figure 5A is a partial top surface view of the X-Y pattern formed on the substrate. In the substrate shown in FIG. 5A , a plurality of openings that are approximately rectangular in plan view are formed in an array. The plurality of openings have approximately the same size. In addition, the X-Y pattern may not only be approximately rectangular when viewed from above, but may also be approximately elliptical when viewed from above. The X-Y pattern is defined as a pattern with a size difference in two orthogonal directions (X direction, Y direction) when viewed from above.

FIG. 5B is used to illustrate the size control example 1 of the X-Y pattern. Figure 5C is used to illustrate the size control 2 of the X-Y pattern. The example in Figure 5B is a control example of reducing the opening size of the long side Y while maintaining the opening size of the short side way to narrow the opening). In the example of Figure 5B, after the X-Y pattern is formed, a film is formed on the substrate in such a way that the Y side becomes shorter. On the other hand, the example in Figure 5C is a control example of maintaining the opening size of the long side Y while reducing the opening size of the short side X (X>Y shrinkage: compared with the Y side, the The method of reducing the amount is to narrow the opening). In the example of Figure 5C, after the X-Y pattern is formed, a film is formed on the substrate in such a way that the X side becomes shorter.

In order to prevent the defective situation shown in FIG. 4C from occurring, it is only necessary to perform the X>Y shrinkage of the opening of the mask in FIG. 4B (see FIG. 5C ) to reduce the reduction of the Y side of the opening as much as possible.

<Implementation>

In view of the above, the plasma processing apparatus of the embodiment is used to form a first film having a film thickness difference according to the state of the pattern formed on the substrate by CVD, and then the first film functions as an inhibitor. The material is used to perform the ALD cycle, and the second film is formed. The plasma treatment device will, for example, use a loading effect to form a first film having a film thickness difference by CVD. Thereafter, when the ALD cycle is executed, the first film is gradually reduced due to the influence of plasma, but a latency corresponding to the film thickness of the first film is generated. Therefore, for example, the second film is formed in a thin width at a position where the first film is formed in a thick width, and the second film is formed in a thick width in a position where the first film is thinly formed. As described above, the plasma processing device of this embodiment uses the latent and loading effects to achieve precise dimensional control.

<Example of plasma treatment apparatus according to embodiment>

FIG. 1 shows an example of the structure of a plasma processing apparatus 10 according to an embodiment. The plasma processing device 10 in this embodiment, for example, as shown in FIG. 1 , has a chamber 21 , which is made of aluminum or the like whose surface has been anodized, and defines a substantially cylindrical processing space inside. Chamber 21 is security grounded. The plasma processing device 10 in this embodiment is configured as a capacitively coupled parallel plate plasma processing device, for example. In the chamber 21, a support base 23 is arranged across an insulating plate 22 made of ceramic or the like. The support base 23 is provided with a base 24 formed of, for example, aluminum or the like and functioning as a lower electrode.

An electrostatic chuck 25 is provided at a substantially central upper portion of the base 24 for adsorbing and holding a semiconductor wafer W, which is an example of a processing target, using electrostatic force. The electrostatic chuck 25 has a structure in which an electrode 26 formed of a conductive film or the like is sandwiched between a pair of insulating layers. The electrode 26 is electrically connected to a DC power supply 27 . In addition, the electrostatic chuck 25 may be provided with a heater (not shown) for heating the semiconductor wafer W.

A focus ring 25 a is arranged on the upper part of the base 24 to surround the electrostatic chuck 25 . The focus ring 25a improves the uniformity of the plasma in the vicinity of the edge of the semiconductor wafer W. The focus ring 25a is formed of, for example, single crystal silicon. An inner wall member 28 is provided around the supporting platform 23 and the base 24 so as to surround the supporting platform 23 and the base 24 . The inner wall member 28 is made of, for example, quartz and has a substantially cylindrical shape.

A refrigerant chamber 29 is formed inside the support stand 23 along the circumferential direction of the support stand 23 , for example. The refrigerant at a predetermined temperature is circulated and supplied to the refrigerant chamber 29 via the piping 30a and the piping 30b from an external cooling unit (not shown). The semiconductor wafer W on the electrostatic chuck 25 can be controlled to a predetermined temperature by circulating a refrigerant of a predetermined temperature in the refrigerant chamber 29 and utilizing heat exchange with the refrigerant. In addition, the heat transfer gas supplied from a gas supply mechanism (not shown) is supplied through the pipe 31 between the upper surface of the electrostatic chuck 25 and the back surface of the semiconductor wafer W placed on the electrostatic chuck 25 . The heat transfer gas is, for example, helium.

An upper electrode 40 is provided above the susceptor 24 that functions as a lower electrode so as to face the susceptor 24 across the processing space in the chamber 21 . The space between the upper electrode 40 and the base 24 and the space surrounded by the chamber 21 is a processing space where plasma is generated. The upper electrode 40 has a top plate 42 that functions as an electrode body, and a top plate support portion 41 that supports the top plate 42 .

The top plate support part 41 is supported by the upper part of the chamber 21 via the insulating member 45 . The top plate support part 41 is formed in a substantially disk shape by, for example, a conductive material with high thermal conductivity such as aluminum whose surface has been anodized. In addition, the top plate support portion 41 also functions as a cooling plate for cooling the top plate 42 heated by plasma generated in the processing space. The top plate support part 41 is formed with a gas inlet 46 for introducing the processing gas; a diffusion chamber 43 for diffusing the processing gas introduced from the gas inlet 46; and a plurality of flow ports 43a for diffusing the processing gas in the diffusion chamber 43. A flow channel for gas to flow downward.

The top plate 42 is made of a silicon-containing material such as quartz and is formed into a substantially disk shape. The top plate 42 is formed with a plurality of gas inlets 42 a penetrating the top plate 42 along the thickness direction of the top plate 42 . Each gas inlet 42a is arranged so as to communicate with any flow port 43a of the top plate support part 41. Thereby, the processing gas supplied into the diffusion chamber 43 is diffused in a spray form and supplied into the chamber 21 through the flow port 43a and the gas inlet 42a.

A plurality of valves 50a to 50c are connected to the gas inlet 46 of the top plate support part 41 via a pipe 47. The valve 50a is connected to a gas supply source 48a via a mass flow controller (MFC) 49a. When the valve 50a is controlled to be in the open state, that is, in the open state, the flow rate of the process gas system supplied from the gas supply source 48a is controlled by the MFC 49a, and is supplied into the chamber 21 through the pipe 47. The gas supply source 48 a supplies, for example, a precursor gas into the chamber 21 .

In addition, the gas supply source 48b is connected to the valve 50b via the MFC 49b. When the valve 50b is controlled to be open, the flow rate of the gas system supplied from the gas supply source 48b is controlled by the MFC 49b, and is supplied into the chamber 21 through the pipe 47. The gas supply source 48b supplies a scrubbing gas into the chamber 21, for example. As the scrubbing gas, for example, inert gases such as argon or nitrogen are used.

In addition, the gas supply source 48c is connected to the valve 50c via the MFC 49c. When the valve 50c is controlled to be open, the flow rate of the gas system supplied from the gas supply source 48c is controlled by the MFC 49c, and is supplied into the chamber 21 through the pipe 47. The gas supply source 48c supplies a reaction gas into the chamber 21, for example.

In addition, when supplying the precursor gas and the reactive gas to the chamber 21, an additional gas may be used for the purpose of reducing the usage amount of the precursor gas and the reactive gas and improving the gas distribution inside the chamber 21. Uniformization and other productivity. As the added gas, an inert gas such as argon or nitrogen can be used. For example, the inert gas supplied from the gas supply source 48b via the valve 50b and MFC 49b may be added to the precursor gas supplied from the gas supply source 48a via the valve 50a and MFC 49a. Furthermore, for example, the inert gas supplied from the gas supply source 48b via the valve 50b and MFC 49b may be added to the reaction gas supplied from the gas supply source 48c via the valve 50c and MFC 49c.

The adjustment of the flow rate of each gas performed by each MFC 49a to 49c and the opening and closing of each valve 50a to 50c are controlled by the control device 60 described below.

The upper electrode 40 is electrically connected to the radio frequency power supply 52 via the matching device 51 . The radio frequency power supply 52 supplies radio frequency power (HF: High Frequency) for plasma excitation at around 40 MHz, for example, to the upper electrode 40 . The radio frequency power supplied from the radio frequency power supply 52 is controlled by a control device 60 described later.

The base 24 functioning as a lower electrode is electrically connected to a radio frequency power source 34 via a matching device 33 . The radio frequency power supply 34 applies bias radio frequency power (LF: Low Frequency) to the base 24 . shoot The frequency power supply 34 supplies radio frequency power with a frequency below 13.56 MHz, such as 2 MHz, to the base 24 through the matching device 33 . By supplying radio frequency power to the base 24 , active species such as ions in the plasma are pulled into the semiconductor wafer W on the electrostatic chuck 25 . The radio frequency power supplied from the radio frequency power supply 34 is controlled by the control device 60 described later.

An opening 78 is formed on the side wall of the chamber 21 , and a pipe 38 is connected to the opening 78 . The piping 38 is divided into two, and one end is connected to the valve 37a, and the other end is connected to the valve 37b. The other end of the valve 37a is connected to the pressure gauge 36a via the piping 38a, and the other end of the valve 37b is connected to the pressure gauge 36b via the piping 38b. The pressure gauges 36a and 36b are, for example, capacitance pressure gauges.

By controlling the valve 37a to the open state, the pipe 38 and the pipe 38a are connected. Thereby, the pressure gauge 36a is exposed to the processing space in the chamber 21 through the opening 78 formed in the side wall of the chamber 21. Thereby, the pressure gauge 36a can measure the pressure within the processing space. On the other hand, by controlling the valve 37a to a closed state, that is, a closed state, the pipe 38 and the pipe 38a are blocked. Thereby, the pressure gauge 36a is shielded from the processing space within the chamber 21.

Furthermore, by controlling the valve 37b to the open state, the pipe 38 and the pipe 38b are connected. Thereby, the pressure gauge 36b is exposed to the processing space in the chamber 21 through the opening 78 formed in the side wall of the chamber 21. Thereby, the pressure gauge 36b can measure the pressure within the processing space. On the other hand, by controlling the valve 37b to the closed state, the pipe 38 and the pipe 38b are blocked. Thereby, the pressure gauge 36b is shielded from the processing space within the chamber 21. The control device 60 described below controls the opening and closing of the valves 37a and 37b.

An exhaust port 71 is provided at the bottom of the chamber 21 , and the exhaust port 71 is connected to an exhaust device 73 via an exhaust pipe 72 . The exhaust device 73 has a vacuum pump such as a DP (Dry Pump) or a TMP (Turbo Molecular Pump), for example, and can depressurize the chamber 21 to a desired degree of vacuum. The exhaust volume and the like of the exhaust device 73 are controlled by the control device 60 described below. For example, when the precursor gas is supplied into the chamber 21 from the gas supply source 48a, the control device 60 controls the valve 37a to be in an open state and the valve 37b to be in a closed state. Furthermore, based on the pressure in the chamber 21 measured by the pressure gauge 36a, the exhaust volume of the exhaust device 73 and the like are controlled, thereby controlling the pressure in the chamber 21 to a predetermined pressure. For another example, when the reaction gas is supplied into the chamber 21 from the gas supply source 48c, the control device 60 controls the valve 37a to a closed state and controls the valve 37b to an open state. Furthermore, based on the pressure in the chamber 21 measured by the pressure gauge 36b, the exhaust volume of the exhaust device 73 and the like are controlled, thereby controlling the pressure in the chamber 21 to a predetermined pressure.

The side wall of the chamber 21 is provided with an opening 74 for loading and unloading the semiconductor wafer W. The opening 74 is openable and closable by the gate valve G. In addition, the inner wall of the chamber 21 is provided with a deposition barrier 76 that is freely removable along the wall surface. Furthermore, a deposition barrier 77 is detachably provided along the outer peripheral surface of the inner wall member 28 . Deposition barriers 76 and 77 prevent reaction by-products (sediments) from adhering to the inner wall of chamber 21 and inner wall members 28 . A conductive member (GND block) 79 connected to the ground is provided at a position of the deposition barrier 76 that is approximately the same height as the semiconductor wafer W placed on the electrostatic chuck 25 . Abnormal discharge in the chamber 21 is prevented by the GND block 79 .

The above-mentioned plasma processing device 10 is integratedly controlled by the control device 60 . The control device 60 has a memory 61 such as a ROM (Read Only Memory) or a RAM (Random Access Memory), such as a CPU (Central Processing Unit); CPU) or DSP (Digital Signal Processor; digital signal processor) and other processors 62 and user interface 63. The user interface 63 includes, for example, a keyboard that allows a user such as a program manager to input instructions for managing the plasma processing device 10 , a display that visually displays the operating status of the plasma processing device 10 , and the like.

The memory 61 stores recipes, including processing condition data for realizing various processes in the plasma processing device 10 , and control programs (software). Furthermore, the processor 62 calls any recipe from the memory 61 and executes it in response to instructions from the user through the user interface 63, thereby controlling each part of the plasma treatment device 10. Thereby, desired processing such as film formation is performed by the plasma processing apparatus 10 . In addition, a recipe or a control program including processing condition data, etc. may be stored in a computer-readable recording medium or the like, or may be transmitted from another device, for example, via a communication line. Computer-readable recording media include hard disks, CDs (Compact Discs), DVDs (Digital Versatile Discs), floppy disks, semiconductor memories, etc.

In addition, here, a plasma processing device 10 using capacitively coupled plasma (CCP: Capacitively Coupled Plasma) as a plasma source is described as an example. However, the technology disclosed in the present invention is not limited to this. Inductively coupled plasma may be used. Plasma treatment device 10 for any plasma source such as ICP (Inductively Coupled Plasma), microwave plasma, etc.

<An example of the flow of the plasma treatment method according to one embodiment>

FIG. 6 is a flowchart showing an example of a general flow of the plasma processing method in the plasma processing apparatus 10 according to the embodiment.

First, a processing target (eg, wafer W) is placed in the chamber 21 of the plasma processing apparatus 10 . The plasma processing apparatus 10 first forms a mask layer on the surface of the treatment object (step S61). Next, the plasma processing apparatus 10 forms a pattern on the mask layer by etching (step S62). The pattern includes, for example, openings having an X-Y pattern. Here, steps S61 and S62 may not be executed in the plasma processing device 10 but may be executed in other devices. For example, after the mask layer and pattern are formed on the wafer W by another device, the wafer W can be moved into the chamber 21 of the plasma processing device 10 to perform the following processing.

Next, the plasma processing apparatus 10 performs CVD on the formed pattern using a gas that forms a film and becomes an inhibitor (step S63, first process). A first film (hereinafter also referred to as an inhibitor layer) whose thickness varies according to the shape of the pattern on the treatment object is formed by CVD. Next, the plasma processing device 10 performs the ALD cycle from above the first membrane a predetermined number of times (step S64, second procedure). The second film is formed on the processing object through the ALD cycle. Thereafter, it is determined whether the plasma processing apparatus 10 satisfies a predetermined condition (step S65). When it is determined that the predetermined condition is satisfied (step S65, Yes), the plasma processing apparatus 10 ends the process. On the other hand, when it is determined that the predetermined condition is not satisfied (step S65, NO), the plasma processing apparatus 10 returns to step S63 and repeats the process. This is a general flowchart of the plasma treatment method in one embodiment. In addition, other processing may be performed after step S64. In the following description, one process from step S63 to step S64 will also be referred to as a sequence.

<Film thickness of first film>

The film thickness of the first film serving as the inhibitor layer formed by CVD in the plasma processing apparatus 10 is determined by various factors. For example, a loading effect may be used whereby the plasma processing device 10 forms the first film into is the desired film thickness. The loading effect is a phenomenon in which the film thickness of the film formed changes due to the density of the pattern. For example, the size of the opening after film formation varies depending on the size of the pattern itself, such as the opening area of the opening. In addition, the size of the opening after film formation varies depending on the shape or arrangement of patterns located around the pattern.

We believe that one of the reasons why the loading effect occurs is because the aspect ratio of the opening determines the angle at which film-forming materials such as gas can invade from the opening side into the opening, and as a result, determines the film formation into the opening. Amount of material. Figure 7 is used to illustrate an example of the loading effect. As shown in FIG. 7 , when the aspect ratio of the opening on the processing target is small, the intrusion angle (Ω) of the material becomes large. On the other hand, when the aspect ratio of the opening is large, the intrusion angle of the material becomes small. Therefore, the film formation amount of each opening changes depending on the intrusion angle. As a result, the film formation amount on the X side of the small opening is smaller than the film formation amount on the Y side of the large opening.

As described above, for example, the smaller the aspect ratio of the opening is, the thicker the film thickness of the first film is. For another example, the larger the solid angle of the opening, the thicker the film thickness of the first film. For another example, the film thickness of the first film changes according to the width or depth of the opening. For example, the wider and shallower the opening, the thicker the film thickness of the first film. In addition, the film thickness of the first film changes according to the density, line diameter, spacing (L/S), etc. of the pattern formed on the processing object.

In addition, the material of the first film formed by the plasma treatment in the embodiment is not particularly limited as long as it hinders the formation of the second film. For example, the first membrane is a hydrophobic membrane. For another example, the first film system contains a film of fluorine (F). For another example, the first film is a film formed of gas containing fluorocarbons. For another example, the first film is a film formed of a gas that does not contain hydrogen. For another example, the first film is a modification film that modifies the surface of the treatment object.

<Film thickness of second film>

When the second film is formed, the first film functions as an inhibitor layer and inhibits chemical adsorption of the precursor gas. Therefore, the film thickness of the second film is controlled in response to the film thickness of the first film.

For example, it is assumed that the thin first film is formed on the X side and the thick first film is formed on the Y side due to the above loading effect. In this case, when the ALD cycle is performed on the first film to form the second film, the time it takes for the first film on the X side to be removed by the ALD cycle is shorter than the time it takes for the first film on the Y side to be removed by ALD. The time it takes to be removed from the cycle. In this way, the timing of the formation of the second film formed by the ALD cycle on the X side starts earlier than the timing of the formation of the second film formed by the ALD cycle on the Y side. As a result, if the same number of ALD cycles are performed on both the X side and the Y side, the film thickness of the second film formed on the X side is thicker than the film thickness of the second film formed on the Y side.

For example, let the film thickness of the first film formed on the Y side be A, and let the film thickness of the first film formed on the X side be B (where A>B). Furthermore, let the film thickness of the first film removed with one ALD cycle in the second process (step S64) be x, and the film thickness of the second film formed with one ALD cycle be y. Moreover, let A=10x and B=2x. In this case, after the ALD cycle is executed 12 times in step S64, the film thickness of the second film formed on the Y side becomes 2y, and the film thickness of the second film formed on the X side becomes 10y. Among them, the amount (film thickness) of the first film formed in the first process (step S63) that is removed in one ALD cycle is different from the film thickness of the second film formed in one ALD cycle (x≠y). therefore, The processing conditions of the first and second procedures, such as the processing time or the number of cycles, can be adjusted taking into account the removal amount of the first film and the formation amount of the second film in the second procedure.

Therefore, if the loading effect can be used to form an inhibitor layer with the same shape as the film system formed on the substrate in Figure 5B, X>Y shrinkage can be achieved through subsequent ALD cycles. Furthermore, if an inhibitor layer with the same shape as the film system formed on the substrate in FIG. 5C can be formed, X<Y shrinkage can be achieved through subsequent ALD cycles.

8A and 8B are used to illustrate the X>Y shrinkage effect obtained by the plasma treatment method of an embodiment. FIG. 8A schematically shows a state in which steps S63 and S64 shown in FIG. 6 are repeated three times to form a second film on the X side. In addition, FIG. 8B schematically shows a state in which steps S63 and S64 shown in FIG. 6 are repeated three times to form a second film on the Y side. In any case, after performing CVD once to form the CF film in step S63, ALD cycles are repeatedly performed a predetermined number of times in step S64, and the sequence of steps S63 and S64 is repeated three times.

As shown in FIG. 8A , among the X sides, the length of the X side is reduced by an average of 8.12 nanometers (nm) by the second film formed on the side walls facing each other sandwiching the X side. That is, a second film with an average thickness of 8.12 nm is formed on the sidewall. On the other hand, in the Y side, the length of the Y side is reduced by an average of 6.37 nanometers by the second film formed on the opposite side walls sandwiching the Y side. That is, a second film with an average thickness of 6.37 nm is formed on the sidewall. We know from Figure 8A and Figure 8B that by repeatedly executing steps S63 and S64, when the opening size of the X side is greatly reduced compared to the opening size of the Y side, the opening sizes of both sides can be reduced. Reduce. That is, we know that X>Y contraction can be achieved. In addition, by further adding the execution of steps S63 and S64 times to increase the X>Y shrinkage effect.

<Examples of other substrate materials>

The plasma treatment method of this embodiment can be applied to treatment objects made of various materials.

FIG. 9 shows a combination of materials to be treated to which the plasma treatment method of this embodiment is applied. Here, it is assumed that the second film is formed by applying the plasma processing method of this embodiment in order to control the size of the mask for a processing target in which an etching layer and a mask are sequentially formed on a substrate. In addition, a stop layer can also be formed between the etched layer and the substrate.

In this case, for example, an etched layer of silicon nitride (SiN), silicon (Si) or silicon germanium (SiGe) can be formed on the silicon substrate, and a mask of silicon dioxide (SiO ₂ ) can be formed. In this case, silicon dioxide (SiO ₂ ) can be used as the second film.

Alternatively, SiO ₂ can be used for the layer to be etched, SiN can be used for the mask, and SiN can be used for the second film. Alternatively, SiO ₂ may be used for the etched layer, and titanium nitride (TiN), tungsten carbide (WC), or zirconium dioxide (ZrO ₂ ) may be used for the mask. In this case, TiN or WC can be used as the second film.

In any combination of materials, CCP and other equipment can be used to achieve processing.

In addition, the plasma processing method of the above embodiment is not only applied to the processing object on which the etching layer and the mask are sequentially formed on the substrate, but can also be applied to processing objects with other structures. For example, it can be applied to silicon-based The etched layer, organic layer, silicon-containing anti-reflective layer, etc. are formed on the board in sequence, and a mask layer such as photoresist is formed on the anti-reflective layer. In this case, for example, a layer formed by multiple patterning can also be inserted on the substrate. Moreover, the pattern size of the mask can also be adjusted using the plasma treatment method of the above embodiment, so that the pattern formed on the mask is aligned with the lines of the layer formed by multiple patterning. The plasma processing method of the above embodiment can be used to precisely adjust the position where the through holes or contacts are formed by adjusting the pattern size of the mask.

<Effects of implementation>

The plasma treatment method of the above embodiment includes a first step and a second step. In the first process, the plasma processing device forms a first film whose thickness varies depending on the distance between the pair of opposing side walls on the side walls of the opening of the treatment object. In the second process after the first process, the plasma treatment device performs the film forming cycle more than once, and forms a second film with a thickness that varies according to the distance between the pair of opposing side walls. Therefore, the plasma processing apparatus can form a second film having a film thickness difference corresponding to the state of the pattern on the treatment object. Therefore, the plasma treatment apparatus of the embodiment can form a second film with a desired film thickness difference by using a loading effect or latency even when it is difficult to form a second film with a desired film thickness difference using a single process. . Therefore, the plasma processing apparatus of the embodiment can realize precise dimensional control of the pattern formed on the substrate.

Furthermore, in the plasma processing method of the embodiment, the plasma processing device, in the first step, forms on the pair of second side walls facing each other at a narrower interval than the pair of first side walls formed on the treatment object. The first film is thinner than the first film formed on the pair of first side walls. Furthermore, in the second step, the plasma treatment device forms a second film on the pair of second side walls that is thicker than the second film formed on the pair of first side walls. Therefore, the plasma processing device of the embodiment can adjust the film thickness according to each of the paired side walls facing each other at different intervals to perform dimensional control, thereby improving pattern accuracy.

Furthermore, in the plasma treatment method of the embodiment, the plasma treatment device forms the first film containing a component that inhibits the formation of the second film in the film formation cycle in the first step. Therefore, the plasma processing apparatus according to the embodiment can precisely control the film thickness of the second film formed subsequently based on the film thickness of the first film.

Furthermore, in the plasma treatment method of the embodiment, the plasma treatment device forms a hydrophobic first film in the first step. In addition, the plasma treatment device forms a first film containing fluorine (F) in the first step. In addition, the plasma treatment device forms the first film using a gas that does not contain hydrogen and contains fluorocarbon (CF) in the first step. As described above, the plasma processing apparatus of the embodiment can form the first film by selecting a material that generates a latent layer of the second film, and can precisely control the size of the pattern.

Furthermore, in the plasma treatment method of the embodiment, the plasma treatment device forms the second film after removing the first film in the second step. Therefore, the plasma processing apparatus according to the embodiment can precisely control the film thickness of the second film based on the film thickness of the first film.

Furthermore, in the plasma processing method of the embodiment, the plasma processing device repeatedly executes the sequence including the first program and the second program one or more times. Therefore, the plasma processing apparatus according to the embodiment can precisely control the thickness of the second film formed by adjusting the number of repetitions of the sequence.

Furthermore, the plasma treatment method of the embodiment includes: a third step, after the second step, the second The film serves as a mask for etching. Therefore, the plasma processing apparatus of the embodiment can perform etching after precisely controlling the size of the mask, that is, the second film, and can precisely control the size of the pattern formed by etching.

Furthermore, in the plasma treatment method of the embodiment, the paired side walls of the treatment target include at least a part of the curved surface. Therefore, the plasma processing apparatus according to the embodiment can precisely control the size of not only linearly formed patterns but also curved patterns.

Furthermore, in the plasma treatment method of the embodiment, in the second step, the atomic layer deposition cycle is performed more than once to form the second film. Therefore, the plasma processing apparatus according to the embodiment can easily control the film thickness of the second film by utilizing the self-limiting property of atomic layer deposition.

Furthermore, in the first step of the plasma treatment method of the embodiment, the plasma treatment device forms the first film by chemical vapor deposition or plasma chemical vapor deposition. Therefore, the plasma processing apparatus of the embodiment can perform processing efficiently.

Furthermore, in the first step of the plasma processing method of the embodiment, the plasma processing device is formed to have an aspect ratio, a solid angle, a width and a depth of the opening, and an area of the opening formed on the processing object. , the thickness difference of at least one of the density of the pattern, the line diameter and the spacing of the first film. Therefore, the plasma processing apparatus according to the embodiment can precisely control the size of the pattern using loading effects caused by various factors.

In addition, the plasma treatment method of the embodiment includes: a film forming process, in which the first film is placed on the treatment object to form a film; and a film forming cycle execution program to execute a film forming cycle for the processing object. Moreover, the film formation cycle is performed using the following: a precursor gas that is not chemically adsorbed on the surface of the first film but is chemically adsorbed on the surface of the treatment object; and a reaction gas that is plasmatized to generate and remove the first film. of free radicals. Therefore, in the plasma treatment method of the embodiment, the thickness of the film formed in the film formation cycle can be controlled using the first film. Therefore, the plasma treatment method of the embodiment can precisely control the size of the pattern.

Furthermore, the plasma treatment method of the embodiment performs a film forming cycle, and the film forming cycle includes a process of simultaneously performing the following processes using the same gas: a removal process to remove the first film by a first predetermined amount on the treatment object; and In the deposition process, a second film is deposited on the processing object in a second predetermined amount that is different from the first predetermined amount. Therefore, the plasma treatment method of the embodiment can realize two different processes of film removal and film formation in one process. Therefore, the plasma treatment method according to the embodiment can efficiently control the size of the pattern.

<Modification 1>

In addition, in the above embodiment, the film thickness of the first film controls the latent time of the film formation cycle, such as the ALD cycle. Alternatively, for example, the film thickness of the first film may be fixed, and the first film may be modified by an ALD cycle to vary the film thickness of the second film.

For example, in step S63 of FIG. 6 , instead of forming a first film whose thickness varies according to the distance between the opposing pairs of side walls, a first film having a uniform thickness is formed on the processing object. At this time, the film forming method can use thermal CVD (thermal chemical vapor deposition; thermal chemical vapor deposition), a method of supplying two organic gases and performing a polymerization reaction by temperature control to form a film, etc.

Furthermore, in step S64 of FIG. 6 , a modification process using a loading effect is performed. For example, in the ALD cycle, in the chemical adsorption step (see FIG. 2A ), silicon-containing gas is supplied to the chamber 21 as a precursor gas. Furthermore, in the reaction step (see FIG. 2C ), a fluorocarbon (C _x F _y , such as C ₄ F ₆ ) and an O-containing gas are supplied to the chamber 21 as reaction gases. A gas scrubbing step of gas scrubbing the chamber 21 may also be performed after the chemical adsorption step and the reaction step.

In this case, where the first film is formed, the silicon-containing gas does not undergo chemical adsorption in the chemical adsorption step, and is subjected to O-containing plasma to remove the first film in the reaction step. Furthermore, during the reaction step, the fluorocarbon contained in the reaction gas is deposited on the first film. On the other hand, where the first film (and the fluorocarbon film deposited on the first film) is removed by the O-containing plasma, in the chemical adsorption step, the silicon-containing gas is chemically adsorbed, and in the reaction step , oxygen free radicals react with silicon-containing molecules to form a SiO ₂ film.

During the reaction step, in the pattern on the processing object, it is difficult for C _x F _y to enter the tight part of the pattern, and it is easy for C _x F _y to enter the loose part of the pattern. Therefore, the denser the pattern (X side), the smaller the amount of C _x F _y film formation, and the looser the pattern (Y side), the greater the C _x F _y film formation amount. In addition, it is difficult for O-containing plasma to enter parts with tight patterns, and it is easy for O-containing plasma to enter parts with loose patterns. Therefore, the denser the pattern (X side), the smaller the removal amount of the first film formed by the O-containing plasma generated by the O-containing gas, and the looser pattern (Y side), the less the first film is removed. The more quantity. The ratio of fluorocarbons and O-containing gases contained in the reaction gas can be adjusted so that the removal speed of the first film on the X side is faster than the removal speed of the first film on the Y side, thereby obtaining the X>Y shrinkage effect ( See Figure 5C). Therefore, through the plasma treatment method of the modified example, the X>Y shrinkage effect can also be obtained (see Figure 5C).

<Modification 2>

In addition, in the above-mentioned embodiment, the processing conditions of the ALD cycle are set so that a sufficient processing time is provided to complete the self-limiting adsorption and reaction on the surface of the processing target. But it is not limited to this, and the processing conditions of the ALD cycle can also be set to not complete the self-limiting adsorption and reaction on the surface of the treatment object. For example, so-called unsaturated ALD (hereinafter also referred to as subconformal ALD) may be used in the second process. Subconformal ALD can be implemented using the following two aspects, for example.

(1) The precursor is adsorbed to the entire surface of the treatment object. It is controlled that the reactant gas system introduced thereafter does not spread over the entire surface of the treatment object.

(2) The precursor is adsorbed to only a part of the surface of the treatment object. The reaction gas introduced subsequently forms a film only on the surface portion where the precursor is adsorbed. Subconformal ALD can be used, and the second film is formed so that the thickness of the second film gradually decreases from top to bottom.

FIG. 10A is used to illustrate the first procedure of the plasma treatment method in Modification 2. FIG. 10B is used to illustrate the second procedure of the plasma treatment method in Modification 2. The X-Y pattern shown in FIG. 10A is set to be the same as the X-Y pattern shown in FIG. 5B , but the film formation amount of the short side X is less than that of the example of FIG. 5B .

The first process of Modification 2 uses CVD to perform the following control: while maintaining the opening size of the short side X, the opening size of the long side Y is reduced (X<Y shrinkage). Thereafter, in the second process, subconformal ALD is used to perform the following control: while reducing the opening size of the short side X, the opening size of the long side Y is maintained (X>Y shrinkage). At this time, the second film is formed on the short side X so that the film thickness gradually becomes thinner from the top to the bottom by unsaturated ALD. In addition, the second film is not formed on the bottom of the short side X. As above As mentioned above, subconformal ALD can be used to suppress the amount of film formation going to the bottom of the object being processed. Furthermore, when subconformal ALD is used, the following relationship is maintained: the thicker the film thickness of the first film, the thinner the film thickness of the second film formed in the same portion. Therefore, according to this plasma treatment method, size control of the X-Y pattern can be achieved.

Like Modification 2, the plasma treatment method of this embodiment can also be formed by performing subconformal ALD cycles more than once in the second process by utilizing the treatment conditions of self-limiting adsorption or reaction on the surface of the unfinished treatment object. Second membrane. Therefore, the plasma treatment method not only controls the X-Y pattern, but also suppresses the amount of film formation at the bottom of the pattern, and can easily perform subsequent processing such as etching.

It should be understood that the embodiments disclosed in this specification are illustrative in all aspects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope of the appended invention claims and the gist thereof.

S61~S65: steps

Claims (16)

A plasma treatment method, including: a first step of forming a first film with a thickness that varies depending on the distance between opposing pairs of side walls on the side walls of an opening of a treatment object; and a second step of forming a first film on the side wall of an opening of a treatment object; After a process, the film forming cycle is performed more than once to form a second film with a thickness that varies according to the distance between the opposing paired side walls; the first process is performed in a manner that is higher than the paired first film formed on the processing object. A first film thinner than the first film formed on the pair of first side walls is formed on the pair of second side walls with narrower side walls facing each other. In the second process, on the pair of second side walls, A second film thicker than the second film formed on the pair of first side walls is formed. For example, in the plasma treatment method of Claim 1, the first step forms the first film containing a component that hinders the formation of the second film in the film formation cycle. For example, in the plasma treatment method of claim 2, the first step forms the hydrophobic first film. For example, in the plasma treatment method of claim 3, the first process forms the first film containing fluorine (F). For example, in the plasma treatment method of claim 4, the first process uses a gas that does not contain hydrogen and contains fluorocarbon (CF) to form the first film. For example, the plasma treatment method of any one of items 1 to 5 of the patent scope is applied for, wherein the second process forms the second film after removing the first film. For example, if the plasma treatment method of any one of items 1 to 5 of the patent scope is applied for, the sequence including the first process and the second process is repeatedly executed more than once. For example, the plasma treatment method of any one of items 1 to 5 of the patent scope includes: a third process, after the second process, etching is performed using the second film as a mask. For example, the plasma treatment method according to any one of items 1 to 5 of the patent application scope, wherein the pair of side walls includes at least a part of the curved surface. For example, the plasma treatment method of any one of items 1 to 5 of the patent scope is applied for, wherein in the second process, atomic layer deposition (Atomic Layer Deposition; ALD) is cycled more than once to form the second film . For example, the plasma treatment method according to any one of items 1 to 5 of the patent scope is applied for, wherein, in the second process, the treatment conditions of the self-limiting adsorption or reaction on the surface of the treatment object are not completed to treat the subsurface The ALD cycle is performed more than once to form the second film. For example, the plasma treatment method of any one of claims 1 to 5, wherein in the first step, the first film is formed by chemical vapor deposition. For example, the plasma treatment method of any one of items 1 to 5 of the patent scope is applied for, wherein the first process forms a process having a shape corresponding to the aspect ratio, solid angle, width and width of the opening formed on the treatment object. The thickness difference of at least one of the depth, the area of the opening, the density of the pattern, and the line diameter and the spacing of the first film. For example, the plasma treatment method of any one of items 1 to 5 of the patent scope is applied for, wherein in the second process, the second film is formed by repeating the following steps: an adsorption step, exposing the treatment object to a precursor body; and a reaction step of exposing the treatment object to a reaction gas. For example, the plasma treatment method of Item 14 of the patent application, wherein the second film is formed subconformally by the following means: during the reaction step, control is performed so that the reaction gas does not spread across the surface of the treatment object ; and/or in the adsorption step, the precursor is adsorbed on only a part of the treatment object. A plasma processing device having: a memory unit that stores a program for executing the plasma processing method according to any one of items 1 to 15 of the patent application scope; and The control unit controls the execution of the program.

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