JP4716370B2 - Low dielectric constant film damage repair method and semiconductor manufacturing apparatus - Google Patents

Description

  The present invention relates to a technique for repairing a damaged layer from which carbon has been detached by plasma or the like on a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen.

  As semiconductor devices tend to be highly integrated year by year, resist materials and exposure techniques have been improved to meet the demands for finer patterns formed on substrates such as semiconductor wafers (hereinafter referred to as wafers). It is getting smaller.

  On the other hand, the device structure is multi-layered for high integration, but it is necessary to reduce the parasitic capacitance to improve the operation speed. Development of membrane materials is underway. As one of the low dielectric constant films, for example, a SiCOH film called a porous MSQ (methyl-hydrogen-silses-quioxane) film having a Si—C bond can be cited.

  Since this SiOCH film is embedded with, for example, copper wiring, the resist mask and the hard mask are used as etching masks, for example, etching is performed with plasma obtained by plasmaizing CF4 gas, and then plasma obtained by converting oxygen gas into plasma. Thus, ashing of the resist mask is performed. FIG. 14 schematically shows this state, in which 100 is a SiOCH film, 101 is a resist mask, and 102 is a hard mask.

  By the way, when plasma processing such as etching or ashing is performed on the SiOCH film 100, for example, the Si—C bond is broken by the plasma on the exposed surface of the SiOCH film 100 exposed to the plasma, that is, the side wall and the bottom surface of the recess. Desorbs from the membrane. Since the Si generated by the bond of C due to the elimination of C is unstable in that state, it is subsequently combined with, for example, moisture in the atmosphere to become Si—OH.

  As described above, the damage layer 103 is formed on the exposed surface of the SiOCH film 100 by the plasma treatment. However, since the carbon content of the damage layer 103 is lowered, the dielectric constant is lowered. Since the line width of the wiring pattern is becoming finer and the thickness of the wiring layer, insulating film, etc. has been reduced, the ratio of the influence of the surface portion on the entire wafer W has increased. This is one of the factors that cause the characteristics of the semiconductor device to deviate from the design value due to a decrease in the dielectric constant.

  On the other hand, as a method for solving such a problem, a technique described in Patent Document 1 is known. This technique performs surface modification of a damaged layer composed of OH groups generated by dry etching using a silazane compound composed of Si—Si bonds and Si—CH 3 bonds. However, this technique is a surface modification that replaces H of the OH group and the silazane compound, and does not return to the state before the plasma treatment, so that the dielectric constant deviates from the design value. Moreover, since the molecule of the silazane compound was large, the molecule bonded to the surface of the film by substitution with H became steric hindrance, and the molecule could not penetrate into the film and could not be modified into the film.

JP-A-2005-340288 ((0010), (0028))

  The present invention has been made under such circumstances, and an object of the present invention is to perform treatment with plasma or the like on a substrate on which an insulating film made of a low dielectric constant film containing silicon, carbon, oxygen and hydrogen is laminated. Another object of the present invention is to provide a technique for repairing a damaged layer from which C has been detached.

The damage repair method of the low dielectric constant film of the present invention is:
A step of positioning an object to be processed in which a damaged layer from which carbon has been desorbed by damaging a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen, in a processing chamber;
A step of supplying a gas for generating CH3 radicals into a housing having a heat source connected to the processing chamber from the outside, and generating CH3 radicals in the housing by thermally decomposing the gas by the heat of the heat sources. When,
Next, the method includes a repairing step of supplying CH3 radicals generated in the housing into the processing chamber and bonding CH3 to the damaged layer.

  The damaged layer mixing step in which the low dielectric constant film is damaged and a damaged layer is formed is a step in which the low dielectric constant film is exposed to plasma.

  The step of exposing the low dielectric constant film to the plasma is an etching process for forming a recess in the low dielectric constant film and / or a resist film made of an organic film formed above the low dielectric constant film is ashed. It is characterized by being an ashing process.

  The object to be processed on which the low dielectric constant film is formed is characterized by being placed in a vacuum atmosphere from the damaged layer mixing process in which the low dielectric constant film is damaged to form a damaged layer to the repair process.

  The damaged layer mixing step and the repairing step are performed in the same processing container.

  Gases for generating CH3 radicals are di-t-alkyl peroxide ((CH3) 3COOC (CH3) 3), methane (CH4), azomethane ((CH3) 2N2, (CH3) 3N), 2,2'-azo. A gas selected from bisisobutylnitrile ((CH3) 2C (CN) N = N (CN) C (CH3) 2), dimethylamine ((CH3) 2NH) and neopentane (C (CH3) 4) It is characterized by that.

The semiconductor manufacturing apparatus of the present invention
A processing chamber for storing an object to be processed on which a damaged layer from which carbon has been detached is formed by damage to a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen; and
Provided within the processing chamber, and mounting table for mounting the object to be processed,
Means for evacuating the inside of the processing chamber,
A housing that is connected to the processing chamber from the outside and includes a heat source for generating CH3 radicals;
A gas introduction pipe for supplying a CH3 radical generating gas into the housing;
Temperature control means for controlling the temperature of the heat source;
A gas for generating CH3 radicals is supplied into the casing, and CH3 radicals generated by thermal decomposition of the gas by the heat of the heat source are supplied from the casing into the processing container, and CH3 is formed in the damaged layer. And a control unit that outputs a control signal so as to be coupled and repaired .

  The present invention can repair a damaged layer by bonding C to a damaged layer from which C is desorbed in a low dielectric constant film containing silicon, carbon, oxygen and hydrogen by supplying CH3 radicals, thereby reducing the film quality. Can be suppressed. Further, for example, a porous film can be repaired by penetrating deeply from the surface portion, and since the lifetime of the CH3 radical is long, a repair process with high in-plane uniformity can be performed on the substrate.

  Next, an example of an apparatus that implements the repair method according to the present invention will be described with reference to FIGS. 1 and 2. This apparatus has a configuration in which a function capable of repairing a SiOCH film is added to a plasma processing apparatus 2 capable of etching and ashing a substrate. The plasma processing apparatus 2 shown in FIG. 1 includes a processing chamber 21 that forms a plasma processing chamber composed of, for example, a vacuum chamber that is a sealed space, and a mounting table 3 that is disposed at the center of the bottom surface of the processing chamber 21. And an upper electrode 4 provided above the mounting table 3 so as to face the mounting table 3.

  The processing chamber 21 is electrically grounded, and an exhaust device 23 serving as a vacuum exhaust means is connected to an exhaust port 22 on the bottom surface of the processing chamber 21 via an exhaust pipe 24. A pressure adjusting unit (not shown) is connected to the exhaust device 23, and the pressure adjusting unit is configured to evacuate the processing chamber 21 by a signal from a control unit 2A described later to maintain a desired degree of vacuum. Has been. A transfer port 25 for the wafer W is provided on the wall surface of the processing chamber 21, and the transfer port 25 can be opened and closed by a gate valve 26.

  A heater block is attached to the inner wall of the processing chamber 21, and the inner wall of the processing chamber 21 is held at a high temperature, for example, 60 ° C. or higher, so that deposits such as fluorocarbons are not deposited.

  The mounting table 3 includes a lower electrode 31 and a support 32 that supports the lower electrode 31 from below, and is disposed on the bottom surface of the processing chamber 21 via an insulating member 33. An electrostatic chuck 34 is provided on the mounting table 3, and the wafer W is mounted on the mounting table 3 through the electrostatic chuck 34. The electrostatic chuck 34 is made of an insulating material, and an electrode foil 36 connected to a high voltage DC power source 35 is provided inside the electrostatic chuck 34. When a voltage is applied to the electrode foil 36 from the high-voltage DC power source 35, static electricity is generated on the surface of the electrostatic chuck 34, and the wafer W placed on the mounting table 3 is electrostatically attracted to the electrostatic chuck 34. It is configured as follows. The electrostatic chuck 34 is provided with a through hole 34 a for discharging a backside gas, which will be described later, to the upper portion of the electrostatic chuck 34.

  A refrigerant flow path 37 through which a predetermined refrigerant (for example, a conventionally known fluorine-based fluid, water, etc.) passes is formed in the mounting table 3, and the mounting table 3 is cooled by the refrigerant flowing through the refrigerant flow path 37. The wafer W mounted on the mounting table 3 is cooled to a desired temperature via the mounting table 3. A temperature sensor (not shown) is attached to the lower electrode 31, and the temperature of the wafer W on the lower electrode 31 is constantly monitored by this temperature sensor.

  In addition, a gas flow path 38 for supplying a heat conductive gas such as He (helium) gas as a backside gas is formed inside the mounting table 3, and the gas flow path 38 is provided at a plurality of locations on the upper surface of the mounting table 3. It is open at. These openings communicate with the through holes 34a provided in the electrostatic chuck 34. When a backside gas is supplied to the gas flow path 38, the backside gas is passed through the through holes 34a. To the top of The backside gas is uniformly diffused over the entire gap between the electrostatic chuck 34 and the wafer W placed on the electrostatic chuck 34, so that the thermal conductivity in the gap is increased.

  The lower electrode 31 is grounded via a high-pass filter (HPF) 3a, and a high frequency power source 31a corresponding to a second high frequency, for example, 2 MHz, is connected to the lower electrode 31 via a matching unit 31b.

  A focus ring 39 is disposed on the outer peripheral edge of the lower electrode 31 so as to surround the electrostatic chuck 34. The plasma is focused on the wafer W on the mounting table 3 through the focus ring 39 when plasma is generated. ing.

The upper electrode 4 is formed in a hollow shape, and a plurality of holes 41 for dispersing and supplying the processing gas into the processing chamber 21 are formed on the lower surface thereof, for example, uniformly distributed to constitute a gas shower head. A gas introduction pipe 42 is provided at the center of the upper surface of the upper electrode 4, and this gas introduction pipe 42 penetrates the center of the upper surface of the processing chamber 21 through an insulating member 27. The gas introduction pipe 42 is branched into four on the upstream side to form branch pipes 42A to 42D, which are connected to gas supply sources 45A to 45D via valves 43A to 43D and flow rate control units 44A to 44D. Yes. A gas introduction pipe 42E described later is connected to a gas supply source 45E through a valve 43E and a flow rate control unit 44E.
The valves 43A to 43E and the flow rate control units 44A to 44E constitute a gas supply system 46 and control the gas flow rate and supply / disconnection of the gas supply sources 45A to 45E by a control signal from the control unit 2A described later. it can. Further, the branch pipes 42A to 42D, the gas supply system 46, and the gas supply sources 45A to 45D constitute means for supplying a plasma processing gas.

  The upper electrode 4 is grounded via a low pass filter (LPF) 47, and the upper electrode 4 has a high frequency power source 4a having a higher frequency than the second high frequency power source 31a, for example, a high frequency power source 4a of 60 MHz, as the first high frequency. It is connected via the matching unit 4b.

  The high frequency from the high frequency power source 4a connected to the upper electrode 4 corresponds to the first high frequency, and is used to convert the processing gas into plasma. From the high frequency power source 31a connected to the lower electrode 31, The high frequency corresponds to the second high frequency, and is for drawing ions in plasma to the surface of the wafer W by applying bias power to the wafer W. The upper electrode 4 and the lower electrode 31 constitute means for converting the plasma processing gas into plasma. The high frequency power sources 4a and 31a are connected to the control unit 2A, and the power supplied to the upper electrode 4 and the lower electrode 31 is controlled according to the control signal.

  Further, a gas heating unit 63 which is a means for supplying a gas for generating CH3 radicals to the wafer W is provided on the side surface of the processing chamber 21. The gas heating unit 63 is, for example, a cylinder as shown in FIG. And is connected to the processing chamber 21 and the gas introduction pipe 42E so that the gas flows from the right side to the left side in the drawing. A supply port 67 for supplying a gas containing CH 3 radicals to the object to be processed is formed between the processing chamber 21 and the gas heating unit 63. A heat source 65 that can heat the gas to 1000 ° C., for example, a tungsten filament is provided in a coil shape along the gas flow path inside the gas heating unit 63, and a power source 66 is connected to the heat source 65 via a housing 64. It is connected. The gas supplied from the gas supply source 45E to the gas heating unit 63 through the gas introduction pipe 42E is thermally decomposed into radicals by the heat source 65 and supplied into the processing chamber 21. . The gas heating unit 63, the gas introduction pipe 42E, the gas supply system 46, and the gas supply source 45E constitute means for supplying CH3 radicals to the object to be processed. The housing 64 may be provided with, for example, a quartz window (not shown), and the temperature of the heat source 65 may be controlled by measuring the temperature of the heat source 65 from the outside with a radiation thermometer (not shown).

  The plasma processing apparatus 2 is provided with a control unit 2A including, for example, a computer. The control unit 2A includes a data processing unit including a program, a memory, and a CPU. Instructions are incorporated so that plasma processing is performed on the wafer W by sending a control signal to each part of the processing apparatus 2 and advancing each step described later. In addition, for example, the memory has an area in which processing parameter values such as processing pressure, processing time, gas flow rate, and power value are written, and these processing parameters are read when the CPU executes each instruction of the program. A control signal corresponding to the parameter value is sent to each part of the plasma processing apparatus 2. This program (including a program related to processing parameter input operation and display) is stored in the storage unit 2B such as a computer storage medium such as a flexible disk, a compact disk, an MO (magneto-optical disk), a hard disk (HD), and the control unit 2A. To be installed.

  Next, an embodiment of a method for manufacturing a semiconductor device of the present invention using the plasma processing apparatus 2 will be described. First, the gate valve 26 is opened, and a 300 mm (12 inch) wafer W is loaded into the processing chamber 21 by a transfer mechanism (not shown). After the wafer W is horizontally placed on the mounting table 3, the wafer W is electrostatically attracted to the mounting table 3. Thereafter, the transfer mechanism is moved away from the processing chamber 21 and the gate valve 26 is closed. Subsequently, backside gas is supplied from the gas flow path 38 to adjust the wafer W to a predetermined temperature. Then perform the following steps:

  Here, the structure of the surface portion of the wafer W is shown in FIG. In this example, a part of the process of forming the copper wiring by the dual damascene is shown. 56 is a Cu wiring, 53 is a SiC film as an etch stopper, 54 is a SiOCH film as an interlayer insulating film, 59 is a SiO 2 film as a hard mask, 51 is a resist mask, and 55 is an opening.

(Step 1: Etching process)
After exhausting the inside of the processing chamber 21 through the exhaust pipe 24 by the exhaust device 23 and maintaining the inside of the processing chamber 21 at a predetermined vacuum level, for example, C4F8 gas, N2 gas and Ar gas are supplied from the gas supply system 46. Subsequently, for example, a first high frequency having a frequency of 60 MHz and a power of 1200 W is supplied to the upper electrode 4 to convert the processing gas, which is a mixed gas of the gas, into a plasma, and a second frequency having a frequency of 2 MHz and a power of 1200 W, for example. A high frequency is supplied to the lower electrode 31.

  This plasma contains active species of a compound of carbon and fluorine, and when the SiO 2 film 59 and the SiOCH film 54 are exposed to the atmosphere of these active species, a compound that reacts with atoms in these films. As a result, the SiO2 film 59, the SiOCH film 54, and the SiC film 53 are etched to form a recess 57 as shown in FIG.

  By being exposed to plasma at this time, the damage layer 60 from which C has been detached is formed on the side wall of the recess 57 formed in the SiOCH film 54 as described above.

(Step 2: Ashing process)
Next, power supply from the high-frequency power sources 4a and 31a is stopped to stop plasma generation in the processing chamber 21, and then supply of gas from the gas supply system 46 is stopped. Next, the inside of the processing chamber 21 is exhausted by the exhaust device 23 to remove the remaining gas, and the inside of the processing chamber 21 is maintained at a predetermined degree of vacuum.

  For example, O2 gas is supplied from the gas supply system 46, and a first high frequency with a frequency of, for example, 60 MHz and power of 300 W is supplied to the upper electrode 4 to turn the gas into plasma, and for example, a frequency of 2 MHz and power of 300 W The second high frequency is supplied to the lower electrode 31.

  With this plasma, the resist mask 51 is ashed and removed as shown in FIG.

  At this time, it is considered that the damage layer 60 formed in the above-described etching process becomes thicker by being exposed to the plasma.

(Step 3: Restoration process)
After the power supply from the high frequency power sources 4a and 31a is stopped and the generation of plasma in the processing chamber 21 is stopped, the supply of gas from the gas supply system 46 is stopped. Next, the inside of the processing chamber 21 is exhausted by the exhaust device 23 to remove the remaining gas, and the inside of the processing chamber 21 is maintained at a predetermined degree of vacuum, for example, 1 Pa (7.5 mTorr) to 10 Pa (75 mTorr). On the other hand, power is supplied from a power source 66 to the heat source 65 of the gas heating unit 63, for example, a tungsten filament, and the temperature is kept at 1000 ° C.

For example, C8H18O2 (di-t-alkyl peroxide (structural formula: (CH3) 3COOC (CH3) 3) gas) is supplied from the gas supply source 45E to the gas heating unit 63 via the gas introduction pipe 42E as a gas for generating CH3 radicals. Then, this gas is thermally decomposed by the heat of the heat source 65. The C8H18O2 gas is converted into CH3 radicals by the reactions shown in the equations (1) and (2) and supplied into the processing chamber 21.
C8H18O2 → 2 (CH3) 3CO (1)
(CH3) 3CO → (CH3) 2CO + CH3 (2)

By maintaining this state for a predetermined time, for example, 20 minutes, the damaged layer 60 generated in the SiOCH film 54 by the plasma in the above-described etching process and ashing process is repaired as shown in FIG. 4D. This reaction is shown in formulas (3) and (4).
SiO− + .CH3 → SiOCH3 (3)
SiO2 + -CH3-> SiOCH3 + O- (4)

  Note that · CH3 represents a CH3 radical. This reaction mechanism is shown in FIG. As shown in FIG. 6A, the Si in the surface of the SiOCH film 54 is disconnected from C by the plasma in the etching process and the ashing process, and an unsaturated bond called a dangling bond is generated. Yes. This dangling bond is also generated inside the SiOCH film 54, and the depth (the film thickness of the damaged layer 60) increases as the amount of plasma to which the SiOCH film 54 is exposed increases. Normally, the dangling bonds are then attached with moisture in the atmosphere, for example as described above, to form Si—OH bonds.

  When CH3 radicals are supplied to the dangling bonds, Si—CH3 bonds are generated as shown in FIG. The SiOCH film 54 is a porous body, and CH3 radicals having small molecules can penetrate into the SiOCH film 54. At this time, the CH3 group bonded to the surface of the above-described SiOCH film 54 is small, and hardly causes steric hindrance to the CH3 radicals that try to enter the SiOCH film 54. For this reason, even after the Si—CH 3 bond is formed on the surface of the SiOCH film 54, the CH 3 radical penetrates into the SiOCH film 54 and bonds with the internal dangling bond to generate the Si—CH 3 bond, and the damage layer 60 Can be repaired.

  On the other hand, the CH3 radical has a structure in which atoms are arranged on the same plane, and deposition of deposits hardly occurs on the SiOCH film 54, so that it can be selectively combined with dangling bonds.

  In addition, since the CH3 radical does not react with other CH3 radicals, other compounds generated by the decomposition of C8H18O2 or dangling bonds that have been repaired once, even if the CH3 radical is supplied unevenly to the wafer W, As can be seen from an experimental example to be described later, since the wafer stays in the processing chamber 21 for a long time, it can be repaired with high uniformity in the plane of the wafer W.

  In this example, the CH3 radical supply port is provided at one location on the side wall of the processing chamber 21, but a plurality of CH3 radical supply ports may be provided in the circumferential direction of the processing chamber 21. It can be expected that the damaged layer 60 is repaired with high uniformity. In such a configuration, the supply amount of radicals can be increased, so that the damaged layer 60 can be repaired quickly. Further, the exhaust ports 22 may be provided at a plurality of locations in the circumferential direction of the wafer W to improve the in-plane uniformity of the wafer W.

  Here, the compounds other than the CH3 radicals generated in the formulas (1) and (2) have a low reaction probability with the SiOCH film 54 and thus do not act on the SiOCH film 54 and are discharged from the exhaust port 22. Conceivable.

  In this example, C8H18O2 gas is used as the gas for generating the CH3 radical. However, the gas is not limited to this. Selectively producing CH3 radicals such as nitrile ((CH3) 2C (CN) N = N (CN) C (CH3) 2), dimethylamine ((CH3) 2NH), neopentane (C (CH3) 4), You may use the gas with little production | generation amount of CH, CH2 and C with a large adhesion coefficient with respect to the SiOCH film | membrane 54 grade | etc.,. Further, in this example, thermal decomposition was performed with a heat source 65 such as a tungsten filament in order to generate CH3 radicals. However, the amount of CH, CH2 and C generated is small other than this, such as decomposition by catalytic CVD or light. Alternatively, a method of selectively generating CH3 radicals may be used.

  After such a repair process for the SiOCH film 54, for example, an organic film serving as a sacrificial film is embedded in the recess 57, and the recess 57 is processed using this organic film to embed Cu to form a wiring structure. To do.

  According to the above-described embodiment, after the etching and ashing are performed on the SiOCH film 54 as the plasma processing, the repairing process for repairing the damaged layer 60 in the SiOCH film 54 generated by the plasma with the CH3 radical is performed. Since the elemental composition ratio of the SiOCH film 54 can be brought close to the composition ratio before the plasma treatment, the decrease in the dielectric constant of the SiOCH film 54 can be suppressed, so that a semiconductor device having the planned electrical characteristics can be obtained. Obtainable.

  As will be apparent from experimental examples described later, this repairing process can be performed on the side wall of a recess such as a groove formed on the surface of the wafer W. When the width of the groove is narrow, for example, it is about 180 nm. Can be repaired.

  Since the repair process using CH3 radicals does not adversely affect the characteristics of other films and semiconductor devices and the plasma processing apparatus 2, the damage layer 60 of the SiOCH film 54 is maintained until the electrical characteristics of the semiconductor devices reach a desired level. Repair can continue.

  Further, the plasma processing apparatus 2 of the present invention performs the etching process, the ashing process, and the repairing process of the SiOCH film 54 in the same processing chamber 21 without carrying the wafer W in and out of the processing chamber 21. This can be done by changing the process conditions. For this reason, by suppressing the adhesion of OH groups to the dangling bonds of Si, it is possible to perform a repair process without performing a process of removing OH groups after the plasma treatment, and further, throughput and installation space of the apparatus. Is also advantageous. The repair process can be performed after the etching process and the ashing process of the SiOCH film 54, but may be performed after each of the etching process and the ashing process.

  In the wafer W to be subjected to plasma processing in the present invention, the resist mask 51 may be formed directly on the insulating film such as the SiOCH film 54, or the SiO 2 film 59 formed on the insulating film such as the SiOCH film 54. For example, an antireflection film for preventing reflection at the time of exposure may be formed between the hard mask and the resist mask 51.

  The repair of the damaged layer 60 in the present invention is not limited to the SiOCH film 54, but is a film made of Si, O, C, and H and causing C desorption by light such as plasma or radiation. For example, MSQ (Methyl-hydrogen-Silses). -Quioxane) film or HSQ (Hydrogen-Silses-Quixane) film or the like.

  In addition, an organic film that is formed above a film such as an interlayer insulating film in which a recess is formed by etching and that is removed by an ashing process is treated with CH3 radicals, and is highly resistant to plasma in the etching process. It can also be modified.

  The present invention is not limited to the application to the etched or ashed SiOCH film 54. For example, the SiOCH film 54 is damaged by peeling off the laminate laminated on the SiOCH film 54. In this case, it may be applied as a subsequent process.

  In order to obtain the CH3 radical used in the present invention, not only the C8H18O2 gas but also the thermal decomposition of a gas having a CH3 group as described above may be used, and not only the thermal decomposition but also light energy or the like may be used. May be.

  As the plasma processing apparatus 2 used in the present invention, a first high frequency for converting the processing gas into plasma is supplied to the lower electrode 31 instead of the upper electrode 4, and an apparatus having a so-called lower two-frequency configuration is adopted. Also good.

  In this example, the gas heating unit 63 is provided outside the processing chamber 21, but is not limited thereto. A gas for generating CH3 radicals may be supplied into the processing chamber 21, and a heat source 65 may be provided in the processing chamber 21 to generate CH3 radicals in the processing chamber 21.

  Here, in this example, the plasma processing apparatus 2 includes the gas heating unit 63, and is configured to perform radical processing and plasma processing in the same processing chamber 21, but each processing is performed in different processing chambers. It doesn't matter. An example of the configuration is shown in FIG. In FIG. 6, reference numeral 70 denotes a semiconductor manufacturing apparatus called a cluster tool or a multi-chamber for performing radical processing and plasma processing. Reference numerals 71 and 72 denote carriers C, which are transfer containers for the wafer W, through the gate door GT. Is a carrier chamber carried in from the atmosphere side, 73 is a first transfer chamber, 74 and 75 are preliminary vacuum chambers, and 76 is a second transfer chamber. These are airtight structures, Are partitioned and can be in a vacuum or inert atmosphere. Reference numeral 77 denotes a first transfer means, and 78 denotes a second transfer means provided so as to transfer an object to be processed between a processing container for plasma processing described later and a processing container for repairing a damaged layer. is there. In addition, a plasma processing apparatus 80 and a radical processing apparatus 81 for repairing the damaged layer 60 generated by the plasma using radicals are airtightly connected to the second transfer chamber 76. A plasma processing chamber (not shown) is provided inside the plasma processing apparatus 80, and a gas supply pipe (not shown) that is a means for supplying a plasma processing gas is connected thereto. In addition, a pair of high-frequency electrodes (not shown), which are means for converting the processing gas supplied from the gas supply pipe into plasma, are provided inside the processing container. Here, a processing apparatus such as a plasma processing apparatus 80 or a radical processing apparatus 81 may be further provided as 82.

  In the semiconductor manufacturing apparatus 70 of FIG. 6, the wafer W in the carrier C is transferred from the first transfer means 77 to the plasma processing apparatus 80 via the preliminary vacuum chamber 74 (or 75) and the second transfer means 78, for example. As described above, plasma processing such as an etching process and an ashing process is performed. Thereafter, the wafer W is carried into the radical processing apparatus 81 via the second transfer means 78, and the above-described repairing process is performed. At this time, the inside of the second transfer chamber 76 is in a vacuum atmosphere, and adhesion of OH groups or the like to Si dangling bonds can be suppressed. The atmosphere in the second transfer chamber 76 is preferably a vacuum atmosphere, but other than that, for example, an inert atmosphere not containing O such as Ar or N 2 may be used.

  Here, the radical processing apparatus 81 for performing the repair process of the wafer W will be briefly described with reference to FIG. In FIG. 7A, reference numeral 82 denotes a processing container for repairing a damaged layer composed of a vacuum chamber. Inside the processing container 82, a mounting table 83 for the wafer W, a heat source 84, and a gas for generating CH3 radicals are provided. A gas supply unit 85 for supplying is provided. An opening 82 a and a gate valve 82 b for transferring the wafer W between the mounting table 83 and the second transfer means 78 described above are provided on the side surface of the processing container 82. An opening 82 c is provided at the lower portion of the processing container 82, and the inside of the processing container 82 can be exhausted by an exhaust device 90 that performs vacuum exhaust through an exhaust pipe 89. Further, a temperature sensor (not shown) and a cooling mechanism for the wafer W are embedded in the mounting table 83 so as to control the temperature of the wafer W. A plurality of small holes 86 are opened in the gas supply unit 85, and the gas is supplied uniformly from the gas supply source 88 toward the mounting table 83 via the gas supply pipe 87. A heat source 84, for example, a tungsten filament is provided between the gas supply unit 85 and the mounting table 83, and as shown in FIG. 7B, connected to a power source (not shown) provided outside the processing container 82, Since the gas supplied from the gas supply unit 85 is thermally decomposed and supplied to the wafer W, it is configured, for example, in an accordion shape so as to increase the contact area with the gas.

  The wafer W mounted on the mounting table 83 through the opening 82 a of the processing container 82 by the second transfer means 78 described above is attracted to the mounting table 83 by the electrostatic chuck provided on the mounting table 83. Is done. Next, the pressure inside the processing vessel 82 is controlled by the exhaust device 90 through the exhaust pipe 89 so that a predetermined degree of vacuum is obtained, and a gas for generating radicals from the gas supply source 88 through the gas supply pipe 87. For example, C8H18O2 gas is supplied into the processing container 82. The gas passes through a heat source 84 heated to, for example, 1000 ° C. in advance, and is thermally decomposed by this heat to mainly generate CH 3 radicals, which are supplied to the wafer W. As described above, the damaged layer 60 is repaired on the wafer W. After the repair is performed for a predetermined time, the wafer W is unloaded from the radical processing apparatus 81 and the semiconductor manufacturing apparatus 70 in the reverse order of the loaded order.

  With the above-described configuration, the time during which the wafer W is processed in the plasma processing apparatus 80 is shortened, so that productivity can be improved. Further, since radicals are supplied from above the wafer W and are supplied to the wafer W very uniformly, the repair within the surface of the wafer W can be performed uniformly.

  In this example, the CH3 radical is generated in the processing container 82 in which the damaged layer 60 is repaired. However, the present invention is not limited thereto, and a separate gas decomposition unit is provided outside the processing container 82, and a heat source 84 is provided in the inside. May be provided so that the gas for generating CH3 radicals is thermally decomposed and supplied into the processing vessel 82.

  Next, experiments conducted for confirming the effects of the present invention will be described. In each experiment, a plasma processing apparatus 2 shown in FIG. 1 was used as an apparatus for performing plasma processing on the wafer W. A detector of a QMS (quadrupole mass spectrometer) is provided on the side wall of the processing chamber 21 so that the type of radicals flowing into the processing chamber 21 can be analyzed.

(Experimental example 1: Confirmation of correlation between processing time and amount of restoration in restoration process)
For the experiment, as shown in FIG. 8A, a damage layer 60 is generated by plasma using a test wafer W in which a SiOCH film 54 is formed on the entire surface of a bare silicon wafer having a diameter of 8 inches (200 mm). Therefore, plasma treatment was performed under the following process conditions. The plasma treatment assumes the etching process, the ashing process, and the like in the above-described step 1 and step 2.
(Plasma treatment)
Upper electrode 4 frequency: 60 MHz
Power of upper electrode 4: 300W
Lower electrode 31 frequency: 2 MHz
Lower electrode 31 power: 0 W
Processing pressure: 1.3 Pa (9.75 mTorr)
Processing gas: O2 = 300 sccm
Processing time: 10 sec
Next, a repair process was performed on the wafer W subjected to the above plasma treatment under the following process conditions.
(Repair process)
Processing gas: C8H18O2 = 300 sccm
Processing pressure: 5.3 Pa (39.75 mTorr)
Temperature of heat source 65: 1000 ° C
The treatment time was set to 8 types of 1 minute, 3 minutes, 5 minutes, 7 minutes, 9 minutes, 15 minutes and 25 minutes.
As a reference example, a sample that was not subjected to the repair process after the plasma treatment was prepared.

Experimental Results After performing the above processing on each wafer W, the wafer W was taken out from the processing chamber 21 into the atmosphere, and the following measurement was performed in a predetermined experimental apparatus. First, as shown in FIG. 8A, the film thickness D of the damaged layer 60 was measured by spectroscopic ellipsometry, and the result is shown in FIG. 9A. Further, elemental analysis of the surface of the SiOCH film 54 was performed by XPS (X-ray photoelectron spectroscopy), and the ratios of the C and O element amounts to the Si element amounts were calculated and shown in FIG. This elemental analysis was also performed on the wafer W before the above plasma treatment, and the result was shown on the left side of FIG.

  In this experiment, in order to measure not only the surface of the SiOCH film 54 but also the inside of the damaged layer 60, a measuring apparatus having a measurement depth equal to or greater than the film thickness of the damaged layer 60 was used. That is, since the repair by the CH3 radical starts from the surface of the SiOCH film 54 and progresses to the inside, the apparatus can measure the entire thickness of the damaged layer 60 in a non-destructive manner. However, D in FIG. 8A is simplified as a film thickness from the surface of the SiOCH film 54.

  In FIG. 9A, it was found that the film thickness D of the damaged layer 60 decreases as the processing time of the repairing process is increased. It was found that the repair progressed to a depth of about 20 nm from the surface of the SiOCH film 54 in the treatment for 25 minutes. From the primary approximation curve calculated based on the data of the experimental results, the film thickness D of the damaged layer 60 becomes zero in about 50 minutes and can be expected to return to the state before the plasma treatment.

  In FIG. 9B, since the ratio of C is reduced by the plasma processing (see processing time 0 minutes), this damage layer 60 is due to the desorption of C from the SiOCH film 54 as described above. Conceivable. In addition, since the ratio of O is increased, it is considered that this also indicates that dangling bonds from which C is eliminated and OH groups in the atmosphere are bonded as described above.

  The elemental amounts of C and O are approaching the values before the plasma treatment by the repair process. However, when the treatment is performed for 25 minutes, the proportion of O is very close to the value before the plasma treatment, but the proportion of C remains at about 2/3 before the plasma treatment. This is because a Si dangling bond once bonded to an OH group or the like has undergone a process such as elimination of the OH group by the CH3 radical and subsequent bonding of the CH3 group. This is thought to be due to the time difference until the coupling.

  Further, from the slopes of the graphs showing the degree of repair shown in FIGS. 9A and 9B, the CH3 radical repairs the surface of the SiOCH film 54 for about 15 minutes, and thereafter, the inside of the SiOCH film 54 is repaired. It is thought that repair is being performed. In other words, the slope of the graph is gentle until about 15 minutes after the repair process, and then becomes a steep slope. Therefore, it is considered that the graph first diffuses on the surface of the wafer W and then penetrates into the interior.

(Experimental example 2: Uniformity of the degree of repair in the plane of the wafer W)
Next, each treatment was performed under the following process conditions.
Example 2
The plasma treatment and the repair process were performed under the same conditions as in Experimental Example 1 except for the following process conditions.
(Repair process)
Processing time: 18 minutes Reference Example 2
Plasma treatment was performed under the same conditions as in Experimental Example 1, and no repair process was performed.

Experimental Results For the processed wafer W, the film thickness D of the damaged layer 60 was measured at each of five points in the X direction and the Y direction of the wafer W by spectroscopic ellipsometry in the same manner as in Experimental Example 1. Here, the CH3 radical supply port faces the center of the wafer W. The direction in which the line connecting the supply port and the center of the wafer W extends is defined as the Y direction, and the direction orthogonal to the Y direction is defined as the X direction. Yes.

  The measurement results are shown in FIG. In the reference example, the film thickness of the damaged layer 60 is almost the same value in both the X direction and the Y direction, and is therefore simplified. As a result, it was found that the damaged layer 60 was repaired approximately 25 nm almost uniformly over the entire surface of the wafer W by the repairing process.

  Although the degree of in-plane repair of the wafer W is slightly non-uniform in the Y direction, the difference is as good as about 10% or less. From this, it can be seen that the CH3 radicals are uniformly supplied to the surface of the wafer W. This is because, as described above, the CH3 radical selectively reacts with the dangling bond of Si and lacks reactivity with other compounds, and the CH3 radical is long enough to uniformly diffuse into the processing chamber 21. It shows that it remains unreacted for a time.

  The cause of the non-uniformity of the degree of repair in the Y direction is considered to be the connection position of the gas heating unit 63 with respect to the processing chamber 21. That is, since the exhaust gas is exhausted from the same direction as the side where the gas heating unit 63 is provided when viewed from the wafer W, CH3 flows to the opposite side of the side where the gas heating unit 63 and the exhaust port 22 are provided. It is considered that the amount of radicals is small and segregation of CH3 radicals occurs in the Y direction. As described above, this is easily improved by changing the position and quantity of the gas heating unit 63 and the exhaust port 22, and it is considered that the uniformity of the degree of repair in the plane of the wafer W can be enhanced.

(Experimental example 3: degree of repair by pattern line width)
Subsequently, a resist mask made of an organic film was stacked above the wafer W shown in FIG. 8A, and an opening having a line width L1 was formed in the resist mask. Thereafter, as shown in FIG. 4B, the etching process and the ashing process were performed on the wafer W under the following process conditions to form the recess 57 having the line width L1, and then the repair process was performed. Moreover, as shown below, as a reference example, an etching process and an ashing process were performed, and a wafer W on which no repair process was performed was also prepared. The line width L1 was set for each of the following examples and comparative examples.
(Etching process)
Upper electrode 4 frequency: 60 MHz
Power of upper electrode 4: 1200W
Lower electrode 31 frequency: 2 MHz
Lower electrode 31 power: 1200W
Processing pressure: 10 Pa (75 mTorr)
Processing gas: C4F8 / N2 / Ar = 4/150/1000 sccm
Processing time: 90 sec
(Ashing process)
Upper electrode 4 frequency: 60 MHz
Power of upper electrode 4: 300W
Lower electrode 31 frequency: 2 MHz
Power of lower electrode 31: 300W
Processing pressure: 1.3 Pa (10 mTorr)
Processing gas: O2 = 300 sccm
Processing time: 45 sec
(Repair process)
Processing gas: C8H18O2 = 300 sccm
Processing pressure: 5.3 Pa (39.75 mTorr)
Temperature of heat source 65: 1000 ° C
Processing time: 10 minutes Example 3-1
L1 = 180 nm.
Example 3-2
L1 = 200 nm.
Example 3-3
L1 = 250 nm.
Reference Example 3-1
The repair process was not performed with L1 = 180 nm.
Reference Example 3-2
The repair process was not performed with L1 = 200 nm.
Reference Example 3-3
The repair process was not performed with L1 = 250 nm.

Experimental Results For each wafer W subjected to the above-described treatment, the line width including the damaged layer 60 on the side wall of the recess 57 as shown in FIG. 8B by immersing in a 1 wt% HF aqueous solution for 30 seconds. FIG. 11 shows L (L = L2−L1) representing the amount of change in the line width including the damaged layer 60 by measuring L2. That is, the damage layer 60 from which carbon has been desorbed from the surface portion of the SiOCH film 54 is dissolved in the HF aqueous solution, while the SiOCH film 54 from which carbon has not been desorbed is not dissolved in the HF aqueous solution. The amount of the damaged layer 60 formed on the film 54 can be known.

  As a result of this experiment, even when the line width L1 was as narrow as 180 nm, the CH3 radicals acted on the side wall of the recess 57, and it was possible to repair the damaged layer 60. On the other hand, it was found that L, which is the damaged layer 60, becomes smaller as the line width L1 formed in the recess 57 becomes narrower. This is considered to be because when the line width is narrow, the time for which the side wall of the recess 57 is exposed to plasma in the etching process and the ashing process is short.

  Further, as the line width L1 becomes narrower, the difference between L after ashing and after repair becomes larger. This indicates that the smaller the line width L1, the more damage layer 60 is repaired by the repairing process. ing. This also suggests that when the line width is narrow, the time for which the side wall of the recess 57 is exposed to plasma in the etching process and the ashing process is short.

(Experimental example 4: Analysis of radical species)
Using the above-described QMS (quadrupole mass spectrometer), the components of radicals supplied into the processing chamber 21 were measured. The experiment was performed under the same process conditions as in the repair process of Experimental Example 1. The result is shown in FIG.

Experimental Results As a result of thermal decomposition of C8H18O2 gas, CH3, C3H6O, and C4H9O were generated in the processing chamber 21 as shown in FIG. Since the peaks of CO and C3H6 could not be identified, they were expressed as CO and C3H6 from the mass number and the estimation of a compound that could be generated. As described above, in the thermal decomposition of this C8H18O2 gas, CH, CH2 and C having a high adhesion coefficient were not generated, and generation of CH3 radicals was observed. It is considered that products other than the CH3 radical are exhausted from the exhaust port 22 without acting on the wafer W.

(Experimental example 5: Change with time of CH3 radical)
The amount of CH3 radicals supplied into the processing chamber 21 was measured using a QMS (quadrupole mass spectrometer) as in Experimental Example 4. In this experiment, in order to ascertain how much the amount of CH3 radicals changes depending on the energization time of the heat source 65, C8H18O2 gas is supplied into the processing chamber 21 from the state where the heat source 65 is not energized in the repair process in Experimental Example 1, The heat source 65 was energized to confirm the change over time in the amount of CH3 radicals. The results are shown in FIG.

Experimental Results The amount of CH3 radicals increased slightly immediately after the heat source 65 was energized, and then increased with a steep slope. This increased amount is considered to correspond to the temperature of the heat source 65, and it is recognized that the temperature of the heat source 65 is stabilized about 30 seconds after the heat source 65 is energized. Moreover, it has confirmed that the CH3 radical was produced | generated by thermal decomposition of C8H18O2 gas.

It is a longitudinal cross-sectional view which shows an example of the plasma processing apparatus of this invention. It is a cross-sectional view which shows an example of the plasma processing apparatus of this invention. It is the schematic which showed an example of the apparatus for producing | generating the CH3 radical in this invention. It is a figure which shows the structure of the wafer W used for the plasma processing of this invention, and each plasma processing. It is a conceptual diagram considered to be an example of the reaction mechanism in the repair process of this invention. It is the conceptual diagram which showed an example of the semiconductor manufacturing apparatus used in this invention. It is the conceptual diagram which showed an example of the radical processing apparatus in this invention. It is a conceptual diagram of the wafer W used for the experiment of this invention. It is a figure which shows the result of Experimental example 1 in this invention. It is a figure which shows the result of Experimental example 2 in this invention. It is a figure which shows the result of Experimental example 3 in this invention. It is a figure which shows the result of Experimental example 4 in this invention. It is a figure which shows the result of Experimental example 5 in this invention. It is a schematic diagram of the wafer W in the conventional plasma processing.

Explanation of symbols

2 Plasma processing apparatus 21 Processing chamber 3 Mounting table 31 Lower electrode 4 Upper electrode 54 SiOCH film 57 Recess 60 Damaged layer 63 Gas heating section 80 Plasma processing apparatus 81 Radical processing apparatus

Claims (8)

A step of positioning an object to be processed in which a damaged layer from which carbon has been desorbed by damaging a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen, in a processing chamber;
A step of supplying a gas for generating CH3 radicals into a housing having a heat source connected to the processing chamber from the outside, and generating CH3 radicals in the housing by thermally decomposing the gas by the heat of the heat sources. When,
And a repairing step of supplying CH3 radicals generated in the housing into the processing chamber to bond CH3 to the damaged layer. The damaged layer, damage repair method of the low dielectric constant film according to claim 1, characterized in that it is formed by exposing the low dielectric constant film to a plasma. The damaged layer, said forming at least one of ashing process for ashing a resist film of a formed above the organic film etching treatment and the low dielectric constant film to form a recess in the low dielectric constant film The method of repairing damage to a low dielectric constant film according to claim 2, wherein: The object to be processed, the low dielectric constant film formed of a damaged layer up to the restoration process, a low dielectric constant film according to any one of claims 1 to 3, characterized in that is placed in a vacuum atmosphere Damage repair method. Damage repair method of the low dielectric constant film according to any one of claims 1 to 4 formation and repair process of the damaged layer is characterized by being carried out in the same processing chamber. Gases for generating CH3 radicals are di-t-alkyl peroxide ((CH3) 3COOC (CH3) 3), methane (CH4), azomethane ((CH3) 2N2, (CH3) 3N), 2,2'-azo. A gas selected from bisisobutylnitrile ((CH3) 2C (CN) N = N (CN) C (CH3) 2), dimethylamine ((CH32NH) and neopentane (C (CH34)) The method for repairing damage to a low dielectric constant film according to any one of claims 1 to 5 . A processing chamber for storing an object to be processed in which a damaged layer from which carbon has been detached is formed by damage to a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen; and
Provided within the processing chamber, and mounting table for mounting the object to be processed,
Means for evacuating the inside of the processing chamber,
A housing that is connected to the processing chamber from the outside and includes a heat source for generating CH3 radicals;
A gas introduction pipe for supplying a CH3 radical generating gas into the housing;
Temperature control means for controlling the temperature of the heat source;
A gas for generating CH3 radicals is supplied into the casing, and CH3 radicals generated by thermal decomposition of the gas by the heat of the heat source are supplied from the casing into the processing container, and CH3 is formed in the damaged layer. A semiconductor manufacturing apparatus , comprising: a control unit that outputs a control signal so as to be coupled and repaired . Gases for generating CH3 radicals are di-t-alkyl peroxide ((CH3) 3COOC (CH3) 3), methane (CH4), azomethane ((CH3) 2N2, (CH3) 3N), 2,2'-azo. A gas selected from bisisobutylnitrile ((CH3) 2C (CN) N = N (CN) C (CH3) 2), dimethylamine ((CH3) 2NH) and neopentane (C (CH3) 4) The semiconductor manufacturing apparatus according to claim 7 .

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