JP2010245562A - Method for recovering damage of low dielectric constant insulating film and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering damage of a low dielectric constant insulating film, the method sufficiently recovering electrical characteristics of the low dielectric constant insulating film itself while suppressing oxidation of buried metal and generation of pattern defaults. <P>SOLUTION: After processing of a low dielectric constant insulating film is completed, a damaged functional group generated in a surface of the low dielectric constant insulating film by the processing is substituted with a hydrophobic functional group (ST.2), and a damaged component present under a dense layer generated in the surface of the low dielectric constant insulating film by the substitution treatment is recovered by using an ultraviolet heat treatment (ST.3). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a damage recovery technique for improving damage generated in a low dielectric constant insulating film.

  Semiconductor integrated circuits have achieved high integration and high performance by miniaturization. However, now that the pattern size has entered the nanometer region, it has become impossible to expect an improvement in the performance of the integrated circuit even if the pattern size is reduced.

  As one technique for solving this problem and improving the performance of an integrated circuit, an insulating film having a lower dielectric constant than an inorganic silicon oxide film (hereinafter referred to as a low-k film or a low dielectric constant in this specification). A technique that utilizes an abbreviated insulating film as an interlayer insulating film has attracted attention. If the dielectric constant of the interlayer insulating film decreases, the parasitic capacitance of the wiring in the integrated circuit decreases. If the parasitic capacitance of the wiring is reduced, the signal transmission speed is improved and the performance of the integrated circuit is improved.

  However, the strength of the low-k film is lower than that of a general inorganic silicon oxide film as an interlayer insulating film. For this reason, the low-k film is damaged during pattern formation etching or photoresist ashing, and its dielectric constant increases.

  As a technique for recovering such damage, Patent Document 1 describes a process of modifying a damaged portion with a silylating agent after etching or ashing, that is, after pattern formation.

JP 2006-49798 A

By the way, as a result of repeated research by the inventors of the present application, it has been found that a low-k film having a damaged layer easily adsorbs moisture (H ₂ O). This is presumably due to the fact that the surface of the low-k film having a damaged layer is hydrophilized. The moisture adsorbed on the low-k film oxidizes metals such as wirings embedded in the low-k film.

  Furthermore, since the surface of the low-k film remains hydrophilic, for example, the cleaning agent is not sufficiently removed during wet cleaning performed after heat treatment, which may contribute to pattern defects.

  If the low-k film is subjected to heat treatment after pattern formation, the adsorbed moisture can be removed, which is effective in suppressing embedded metal oxidation and pattern defects.

  However, only the heat treatment cannot sufficiently recover the damage component in the damaged layer, the dielectric constant remains shifted to a high level, and the electrical characteristics of the low-k film itself are not sufficiently recovered.

  The present invention relates to a low dielectric constant insulating film damage recovery method capable of sufficiently recovering the electrical characteristics of the low dielectric constant insulating film itself while suppressing oxidation of embedded metal and occurrence of pattern defects, and the damage recovery. An object of the present invention is to provide a method of manufacturing a semiconductor device using the method.

  In order to solve the above-described problem, the low dielectric constant insulating film damage recovery method according to the first aspect of the present invention occurs in a low dielectric constant insulating film made of an insulating film having a lower dielectric constant than that of an inorganic silicon oxide film. A damage recovery method for a low dielectric constant insulating film that recovers damage, wherein the low dielectric constant insulating film is processed, and the low dielectric constant insulating film is processed, and then the surface of the low dielectric constant insulating film is processed. Damaged functional groups generated by the treatment are replaced with hydrophobic functional groups, and damage components existing under the dense layer produced by the substitution treatment on the surface of the low dielectric constant insulating film are subjected to ultraviolet heat treatment. Let me recover.

  According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: forming a low dielectric constant insulating film made of an insulating film having a dielectric constant lower than that of an inorganic silicon oxide film on a semiconductor substrate; After the dielectric constant insulating film is processed and a predetermined pattern is formed on the low dielectric constant insulating film, and after the low dielectric constant insulating film is processed, the low dielectric constant insulating film is formed on the surface of the low dielectric constant insulating film in the processing step. A step of replacing a damaged functional group with a hydrophobic functional group, and a step of recovering a damage component existing under the dense layer generated on the surface of the low dielectric constant insulating film in the replacement step using an ultraviolet heat treatment And.

  According to the present invention, a method for recovering damage to a low dielectric constant insulating film capable of sufficiently recovering the electrical characteristics of the low dielectric constant insulating film itself while suppressing the oxidation of embedded metal and the occurrence of pattern defects, and this A method for manufacturing a semiconductor device using the damage recovery method can be provided.

1 is a flowchart showing a basic flow of a damage recovery method for a low dielectric constant insulating film (Low-k film) according to a first embodiment of the present invention; Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film which concerns on 1st Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film which concerns on 1st Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film which concerns on 1st Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film which concerns on 1st Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film which concerns on 1st Embodiment 7A is a cross-sectional view schematically showing the Low-k film 5 immediately after the ashing of the photoresist film, and FIG. 7B schematically shows the Low-k film 5 immediately after the LKR treatment. Cross section The figure which shows an example of a LKR processing apparatus The figure which shows an example of an ultraviolet-ray heat processing apparatus The figure which shows the output wavelength of the ultraviolet heat treatment equipment FIG. 11A is a diagram illustrating an example of the effect according to the first embodiment, and FIG. 11B is a diagram illustrating processing conditions. A flow chart showing a basic flow of a damage recovery method for a low dielectric constant insulating film (Low-k film) according to a second embodiment of the present invention. Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film concerning 2nd Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film concerning 2nd Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film concerning 2nd Embodiment Sectional drawing which shows the main manufacturing processes of an example of the manufacturing method of the semiconductor device using the damage recovery method of the low dielectric constant insulating film concerning 2nd Embodiment FIG. 17A is a cross-sectional view schematically showing the Low-k film 5 immediately after the ashing of the photoresist film, and FIG. 17B schematically shows the Low-k film 5 immediately after the LKR treatment. Cross section The figure which shows an example of the ultraviolet decomposition processing device The figure which shows the output wavelength of the UV decomposition processing equipment The figure which shows an example of the effect by 2nd Embodiment. A flow chart showing a basic flow of a low dielectric constant insulating film (low-k film) damage recovery method according to a third embodiment of the present invention.

  Hereinafter, a damage recovery method for a low dielectric constant insulating film according to an embodiment of the present invention and a method for manufacturing a semiconductor device using the damage recovery method will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a flowchart showing a basic flow of a damage recovery method for a low dielectric constant insulating film (Low-k film) according to a first embodiment of the present invention.

  The Low-k film damage recovery method according to the first embodiment basically follows the following flow.

  First, ST. As shown in FIG. 1, the low-k film is processed. During this processing, the Low-k film is damaged, and a damaged layer containing a damaging functional group is formed on the surface thereof.

  Next, ST. As shown in FIG. 2, ST. The damaging functional group generated by the processing shown in 1 is substituted with a hydrophobic functional group.

  Next, ST. As shown in FIG. 3, ST. The damage component existing under the dense layer generated by the substitution process shown in 2 is recovered.

  An example of a method for manufacturing a semiconductor device using such a damage recovery method will be described below.

  2 to 6 are cross-sectional views illustrating an example of a method of manufacturing a semiconductor device using the damage recovery method for a low dielectric constant insulating film according to the first embodiment in the order of main manufacturing steps.

  First, as shown in FIG. 2, an interlayer insulating film 2 is formed on a semiconductor substrate (semiconductor wafer) 1, for example, a silicon substrate. Next, a groove (wiring trench) 3 in which the wiring is embedded is formed in the interlayer insulating film 2 by using a photolithography method. Next, the wiring 4 is formed by embedding metal, for example, copper in the groove 3 by using a damascene method.

  In the present specification, the semiconductor substrate 1 itself or the semiconductor substrate 1 and the semiconductor element formed in the semiconductor substrate 1 and the wiring 4 formed on the semiconductor substrate 1 are described. A structure including the interlayer insulating film 2 to be insulated is defined as a semiconductor substrate 100.

  Next, the Low-k film 5 is formed on the semiconductor substrate 100.

  The low-k film 5 of this example is an insulating film having a dielectric constant lower than that of the inorganic silicon oxide film. For example, the dielectric constant k of the inorganic silicon oxide film deposited using the CVD method with the source gas being TEOS is about 4.2. Therefore, the dielectric constant k of the Low-k film 2 of this example is less than 4.2.

  An example of an insulating film having a dielectric constant k of less than 4.2 is an organic insulating film. The organic insulating film includes a substituent that replaces a part of the main bond with another bond that lowers the dielectric constant k. As an example of such an organic insulating film, there is an organic silicon oxide film containing a substituent that replaces a part of the main bond “Si—O” with another bond that lowers the dielectric constant k.

An example of the substituent is an alkyl group (—C _n H _{2n + 1} ). In the organic silicon oxide film containing an alkyl group, a part of the “Si—O” bond is replaced by “Si—C _n H _{2n + 1} ”, so that the dielectric constant k is lower than that of the inorganic silicon oxide film. An example of an alkyl group is a methyl group (—CH ₃ ). In the organic silicon film containing a methyl group, a part of the main bond “Si—O” is replaced with “Si—CH ₃ ”.

An example of an organic silicon oxide film containing a methyl group is MSQ (Methylsilses-quioxane). The MSQ is formed by using not only a part of “Si—O” bond is replaced by “Si—CH ₃ ” but also a coating method (Spin On Dielectric: SOD). It is easy to make it porous compared to the case of forming. By making it porous, the dielectric constant k further decreases. The dielectric constant k of MSQ is about 2.7 to 2.9.

  Furthermore, MSQ formed using the SOD method, for example, by adding a thermally unstable substance at the time of formation, and thermally decomposing and disappearing this substance, the pores (pores) are more positively formed. There is a porous MSQ that is more porous. The dielectric constant k of the porous MSQ is about 1.8 to 2.5. The low-k film 5 of this example is a porous MSQ.

  Next, a photoresist is applied on the Low-k film 5 to form a photoresist film 6. Next, an opening 7 is formed in the photoresist film 6 by using a photolithography method.

  Next, as shown in FIG. 3, the low-k film 5 is etched, for example, anisotropically etched, using the photoresist film 6 in which the opening 7 is formed as a mask, and through holes (vias) reaching the wiring 4 are formed. 8) (also called holes or contact holes). An example of anisotropic etching is RIE (Reactive Ion Etching).

  When the low-k film 5 is etched, the low-k film 5 is damaged. The damaged part is schematically indicated by reference numeral 9 (x mark, hereinafter referred to as damage component 9). Damage components 9 when the Low-k film 5 is etched are often generated on the surface of the Low-k film 5 exposed to the through holes 8.

  Next, as shown in FIG. 4, the photoresist film 6 is removed by, for example, ashing.

  Even when the photoresist film 6 is ashed, the Low-k film 5 is damaged. The damage component 9 when the photoresist film 6 is ashed is generated on the entire surface of the low-k film 5.

  Next, as shown in FIG. 5, a recovery process for recovering the damage component 9 generated in the Low-k film 5 is performed. In the present specification, the recovery processing is hereinafter referred to as LKR (Low-k Restoration) processing. The damage component 9 is a damaging functional group. In this example, the damaging functional group is a “Si—OH” bond. Further, the surface of the Low-k film 5 in which many “Si—OH” bonds are generated remains hydrophilic. In the LKR treatment of this example, the damaging functional group is replaced with a hydrophobic functional group. In this example, the LKR process was performed under the following conditions.

Reaction gas: TMSDMA (Trimethylsilyldimethylamine)
Processing chamber pressure: 50 Torr (absolute pressure)
Wafer temperature: 150 ° C
Processing time: 150 sec
An example of the LKR processing apparatus used for the LKR processing is shown in FIG.

  As shown in FIG. 8, the LKR processing apparatus 300 includes a chamber 301 that accommodates the wafer W, and a wafer mounting table 302 is provided below the chamber 301. A heater 303 is embedded in the wafer mounting table 302, and the wafer W mounted thereon can be heated to a desired temperature. Wafer lift pins 304 are provided on the wafer mounting table 302 so as to protrude and retract, and the wafer W can be positioned at a predetermined position spaced upward from the wafer mounting table 302 when the wafer W is loaded and unloaded. It has become.

  An inner container 305 is provided in the chamber 301 so as to partition a narrow processing chamber S including the wafer W, and a reaction gas is supplied to the partitioned processing chamber S. A gas introduction path 306 extending vertically is formed at the center of the inner container 305.

A gas supply pipe 307 is connected to an upper portion of the gas introduction path 306. A pipe 309 extending from the reactant supply source 308 and a carrier gas made of Ar, N ₂ gas, or the like are supplied to the gas supply pipe 307. A pipe 311 extending from the carrier gas supply source 310 is connected. The pipe 309 is provided with a vaporizer 312, a mass flow controller 313, and an on-off valve 314 that vaporize the reactant in order from the reactant supply source 308 side. On the other hand, a mass flow controller 315 and an opening / closing valve 316 are provided in the pipe 311 in order from the carrier gas supply source 310 side. Then, the reaction gas vaporized by the vaporizer 312 is carried by the carrier gas and introduced into the processing chamber S through the gas supply pipe 307 and the gas introduction path 306. During the processing, the wafer W is heated to a predetermined temperature by the heater 303. In this case, the wafer temperature (substrate temperature) can be controlled from room temperature to 300 ° C., for example.

  An air introduction pipe 317 is provided so as to extend from the air atmosphere outside the chamber 301 into the internal container 305 inside the chamber 301. The atmosphere introduction pipe 317 is provided with a valve 318, and the atmosphere is introduced into the processing chamber S by opening the valve 318.

  A gate valve G is provided on the side wall of the chamber 301, and the wafer W is loaded and unloaded by opening the gate valve G. An exhaust pipe 320 is provided at the peripheral edge of the bottom of the chamber 301, and the inside of the processing chamber S can be exhausted through the exhaust pipe 320 by a vacuum pump (not shown), and can be controlled to, for example, 10 Torr or less. It has become. The exhaust pipe 320 is provided with a cold trap 321. Further, a baffle plate 322 is provided in a portion between the wafer mounting table 302 and the upper chamber wall.

In the LKR process of this example, since the reaction gas 10 (see FIG. 5) having a bond of Si and CH ₃ is supplied into the process chamber S, “Si—OH” bonds are formed on the surface of the Low-k film 5. A substitution reaction occurs in which the Si—CH ₃ ″ bond is substituted. As a result, “Si—OH” bonds generated on the surface of the low-k film 5 are reduced, and the damage component 9 is recovered. Further, the surface of the Low-k film 5 in which many “Si—CH ₃ ” bonds are generated becomes hydrophobic.

  As described above, in the LKR treatment, the damaging functional group is substituted with the hydrophobic functional group, so that the damaging functional group can be reduced and the damage can be recovered.

  However, the inventors of the present application have found that it is possible to further reduce the damage functional groups generated in the Low-k film 5 and further recover the damage. One reason why damage can be further recovered will be described with reference to FIGS. 7 (A) and 7 (B).

  7A is a cross-sectional view schematically showing the Low-k film 5 immediately after the ashing of the photoresist film, and FIG. 7B schematically shows the Low-k film 5 immediately after the LKR treatment. It is sectional drawing.

  As shown in FIG. 7A, damage components (damaging functional groups) 9 are generated on the surface of the Low-k film 5 immediately after ashing. When the LKR process is performed on the Low-k film 5 in this state, as shown in FIG. 7B, the damage component (damaging functional group) 9 on the surface of the Low-k film 5 becomes a hydrophobic functional group. Replaces and recovers damage. However, on the surface of the low-k film 5, the above substitution reaction occurs, and at the same time, the low-k film 5 is condensed, and a region where density is increased, so-called dense layer 5a is gradually generated. Since the dense layer 5a has a high density, the supply of the reaction gas 10 is hindered. For this reason, the substitution reaction of the damage component (damaging functional group) 9 is difficult to proceed under the dense layer 5a. If the damage component 9 existing under the dense layer 5a can be recovered, the damage received by the low-k film 5 can be further recovered.

  Therefore, in this example, as shown in FIG. 6, a secondary recovery process for recovering damage components existing under the dense layer 5a generated by the LKR process on the surface of the low-k film 5 is performed (hereinafter, this specification). This is called secondary LKR processing in the book).

  In this example, ultraviolet irradiation was used as the secondary LKR treatment. An example of ultraviolet irradiation is ultraviolet heat treatment. The secondary LKR treatment was performed under the following conditions.

Ultraviolet light: Long wavelength broad wave (high pressure mercury lamp used)
Processing chamber atmosphere: Under nitrogen gas atmosphere Processing chamber pressure: Atmospheric pressure (760 Torr (absolute pressure))
Wafer temperature: 350 ° C
Processing time: 180 sec
An example of an ultraviolet heat treatment apparatus used for the secondary LKR treatment is shown in FIG.

As shown in FIG. 9, the ultraviolet heat treatment apparatus 400 includes a chamber 401 that accommodates a wafer W, and a wafer mounting table 402 is provided below the chamber 401. A heater 403 is embedded in the wafer mounting table 402. A wafer W is mounted on the wafer mounting table 402 via a proximity 404, and the wafer W can be heated to a desired temperature by a heater 403. In this example, the wafer W was heated to 350 ° C. as described above. A gas supply pipe 405 and a gas exhaust pipe 406 are connected to the chamber 401 so that a desired gas can be supplied to the processing chamber S partitioned in the chamber 401. In this example, as described above, the atmosphere in the processing chamber S is a nitrogen gas (N ₂ ) atmosphere. An ultraviolet lamp 408 is attached to the upper portion of the chamber 401 via an air-cooled cooling unit 407 so that the wafer W in the processing chamber S can be irradiated with ultraviolet rays. A high pressure mercury lamp was used as the ultraviolet lamp 408 in this example. FIG. 10 shows the output wavelength of the high-pressure mercury lamp.

  As shown in FIG. 10, the high-pressure mercury lamp used in this example outputs light having a wavelength of approximately 200 nm to 800 nm. This light includes an ultraviolet region having a wavelength in the range of 200 nm to 380 nm. This is a long wavelength class of ultraviolet rays. The high-pressure mercury lamp emits a plurality of strong mercury emission lines for each wavelength. A strong mercury emission line is as shown in FIG. 10, and in the range of the ultraviolet region, a plurality of mercury emission lines having wavelengths of about 254 nm, about 297 nm, about 302 nm, about 313 nm, about 334 nm, and about 365 nm are included. In the present specification, ultraviolet light including a plurality of emission lines having strong wavelengths is referred to as broad wave ultraviolet light.

  Thus, in this example, ultraviolet irradiation is used as the secondary LKR treatment, and a specific example is ultraviolet heating treatment, the wafer temperature is 350 ° C., and the atmosphere in the processing chamber S is nitrogen, and the wavelength is 200 nm or more and 380 nm or less. Broad-wave ultraviolet rays within the range of 180 nm were irradiated for 180 seconds. FIG. 11A shows the effect of damage recovery for each sample. FIG. 11B shows a test state for each sample.

  As shown in FIGS. 11A and 11B, the initial dielectric constant (k-Value) of the Low-k film 5, in this example, the porous MSQ, was 2.44 ( Sample A).

  When the low-k film 5 was etched (Etch) and then the photoresist film 6 was subjected to oxidation ashing (Ash), the dielectric constant of the porous MSQ increased to 3.03 (Sample B).

  When the above-mentioned LKR treatment (restoration treatment) was performed after the etching and the oxidation ashing, the dielectric constant of the porous MSQ recovered to 2.91 (Sample C).

  After the etching and the oxidation ashing, the dielectric constant of the porous MSQ recovered to 2.87 when the above-described ultraviolet heat treatment (UV treatment) was performed (Sample D).

  After the etching and the oxidation ashing, the dielectric constant of the porous MSQ was recovered to 2.83 when the above-mentioned LKR treatment was performed and the above-described ultraviolet heat treatment was performed (Sample E).

  In this way, the low-k film 5 after processing is subjected to ultraviolet heat treatment as the secondary LKR treatment in addition to the LKR treatment, so that the dielectric constant is reduced as compared with the case of only the LKR treatment. It was possible to improve by 0.2.

  As described above, according to the damage recovery method for the low dielectric constant insulating film (Low-k film) according to the first embodiment, the damaging functional group generated on the surface of the low dielectric constant insulating film by the processing treatment is converted to the hydrophobic functional group. Substitution with the group makes the surface of the low-k film after processing hydrophobic. For this reason, compared with the case where the surface of the Low-k film remains hydrophilic, the cleaning agent can be more sufficiently removed during the wet cleaning. If the cleaning agent can be sufficiently removed, the cause of pattern defects can be reduced and the occurrence of pattern defects can be suppressed.

  In addition, the above replacement treatment may cause a dense layer on the surface of the low dielectric constant insulating film, and damage components existing under this dense layer are recovered using an ultraviolet heat treatment. For this reason, compared with the case where the damage component existing under the dense layer is not recovered, the damage component can be reduced, and the electrical characteristics of the low dielectric constant insulating film itself can be sufficiently recovered.

Furthermore, since the damage recovery method involves a heat treatment for heating the substrate, moisture adsorbed on the damaged layer of the low dielectric constant insulating film, particularly H ₂ O, can be removed, and the metal caused by the adsorbed moisture Oxidation can also be prevented.

  As described above, according to the damage recovery method for the low dielectric constant insulating film according to the first embodiment, the electrical conductivity of the low dielectric constant insulating film itself is suppressed while suppressing the oxidation of the embedded metal and the generation of pattern defects. The characteristics can be fully recovered.

  If a semiconductor device is manufactured using such a damage recovery method, the manufactured semiconductor device can include, for example, an interlayer insulating film having a sufficiently low dielectric constant, a high signal transmission speed, A high performance semiconductor integrated circuit can be obtained.

  Moreover, since the occurrence of pattern defects is suppressed, the high-performance semiconductor integrated circuit can be manufactured with a high yield.

  Furthermore, since the amount of adsorbed moisture in the interlayer insulating film is reduced, the oxidation of the metal wiring embedded in the interlayer insulating film is also suppressed. By suppressing the oxidation of the metal wiring, it is possible to extend the life of the high-performance semiconductor integrated circuit.

(Second Embodiment)
FIG. 12 is a flowchart showing a basic flow of a damage recovery method for a low dielectric constant insulating film (Low-k film) according to the second embodiment of the present invention.

  The low-k film damage recovery method according to the second embodiment basically follows the following flow.

  First, ST. As shown in FIG. 21, the low-k film is processed. During this processing, a polymer layer is generated on the surface of the low-k film. Furthermore, the Low-k film is damaged, and a damage layer containing a damaging functional group is formed on the surface thereof.

  Next, ST. As shown in FIG. 22, ST. The polymer layer produced by the processing shown in 21 is decomposed.

  Next, ST. As shown in FIG. 23, after decomposing the polymer layer, ST. The damaging functional group generated by the processing shown in 21 is substituted with a hydrophobic functional group.

  An example of a method for manufacturing a semiconductor device using such a damage recovery method will be described below.

  13 to 16 are cross-sectional views showing an example of a manufacturing method of a semiconductor device using the damage recovery method for a low dielectric constant insulating film according to the second embodiment in the order of main manufacturing steps.

First, the Low-k film 5 is formed on the semiconductor substrate 100 in accordance with the manufacturing method described with reference to FIG. The Low-k film 5 in the second embodiment can be the same as the Low-k film 5 described in the first embodiment, and has a dielectric constant lower than that of the inorganic silicon oxide film. An insulating film having a rate k of less than 4.2 is used. An example of the insulating film having a dielectric constant k of less than 4.2 is an organic insulating film including a substituent that substitutes a part of the main bond with another bond that lowers the dielectric constant k, as in the first embodiment. It is. An example of such an organic insulating film is an organic material including a substituent that substitutes a part of the main bond “Si—O—Si” with another bond that lowers the dielectric constant k, as in the first embodiment. A silicon oxide film can be raised. An example of the substituent is an alkyl group (—C _n H _{2n + 1} ), and an example of the alkyl group is a methyl group (—CH ₃ ). An example of an organic silicon oxide film containing a methyl group is an MSQ or a porous MSQ, as in the first embodiment. The Low-k film 5 in this example is a porous MSQ.

  Next, as shown in FIG. 13, according to the manufacturing method described with reference to FIG. 3, the low-k film 5 is formed using the photoresist film 6 having the openings 7 formed on the low-k film 5 as a mask. Is etched, for example, anisotropically etched to form a through hole (also referred to as a via hole or a contact hole) 8 reaching the wiring 4. An example of anisotropic etching is RIE.

  Also in the second embodiment, the low-k film 5 is damaged by the etching, and the damage component 9 is generated on the surface thereof, and the polymer layer 5 b is generated on the surface of the low-k film 5. In the stage shown in FIG. 13, the polymer layer 5 b is generated on the surface of the low-k film 5 exposed to the through hole 8.

  Next, as shown in FIG. 14, the photoresist film 6 is removed by, for example, ashing.

  Also in the second embodiment, the low-k film 5 is damaged by ashing, and the polymer layer 5 b is generated on the surface of the low-k film 5. As shown in FIG. 14, when the photoresist film 6 is ashed, damage components 9 are generated on the entire surface of the Low-k film 5, and a polymer layer 5 b is generated on the entire surface of the Low-k film 5. .

  In this state, even if the LKR process described in the first embodiment is performed on the Low-k film 5, damage is not recovered or is difficult to recover. The reason for this will be described with reference to FIGS. 17 (A) and 17 (B).

  FIG. 17A is a cross-sectional view schematically showing the Low-k film 5 immediately after the ashing of the photoresist film, and FIG. 17B schematically shows the Low-k film 5 immediately after the LKR treatment. It is sectional drawing.

  As shown in FIG. 17A, damage components (damaging functional groups) 9 are generated on the surface of the Low-k film 5 immediately after ashing, and a polymer layer 5b is generated. When the LKR process is performed on the Low-k film 5 in this state, as shown in FIG. 17B, the supply of the reaction gas 10 is blocked by the polymer layer 5b, and the reaction gas 10 is damaged by damage components (damaging functionalities). Base) 9 is not reached or difficult to reach. For this reason, in the Low-k film 5 in which the polymer layer 5b is formed on the surface, the substitution reaction of the damage component (damaging functional group) 9 does not proceed or is difficult to proceed. If the damage component 9 existing under the polymer layer 5b can be recovered, the damage received by the Low-k film 5 can be recovered.

  Therefore, in this example, as shown in FIG. 15, a decomposition process for decomposing the polymer layer 5 b generated on the surface of the low-k film 5 is performed.

  In this example, ultraviolet irradiation was used as the decomposition treatment. An example of ultraviolet irradiation is ultraviolet decomposition treatment. This ultraviolet decomposition treatment was performed under the following conditions.

Ultraviolet light: Short wavelength single wave (using excimer lamp)
Processing chamber atmosphere: Under atmospheric atmosphere Processing chamber pressure: Atmospheric pressure (760 Torr (absolute pressure))
Wafer temperature: Room temperature (no temperature control)
Processing time: 10 sec
An example of the ultraviolet heat treatment apparatus used for the decomposition treatment is shown in FIG.

As shown in FIG. 18, the ultraviolet heat treatment apparatus 500 includes a chamber 501 that accommodates a wafer W, and a wafer mounting table 502 is provided below the chamber 501. A wafer W is mounted on the wafer mounting table 502 via a proximity 504. A gas supply pipe 505 and a gas exhaust pipe 506 are connected to the chamber 501 so that a desired gas can be supplied to the processing chamber S partitioned in the chamber 501. In this example, as described above, the atmosphere in the processing chamber S is an air atmosphere. Note that the atmosphere in the processing chamber S is not limited to an air atmosphere, and may be a nitrogen gas (N ₂ ) atmosphere. In the case of a nitrogen gas atmosphere, nitrogen gas may be supplied from the gas supply pipe 505 into the processing chamber S. An ultraviolet lamp 508 is attached to the upper portion of the chamber 501 via a water-cooling type cooling unit 507 so that the wafer W in the processing chamber S can be irradiated with ultraviolet rays. The ultraviolet lamp 508 is accommodated in a lamp chamber L partitioned from the processing chamber S by quartz glass 509. A gas supply pipe 510 and a gas exhaust pipe 511 are connected to the lamp chamber L so that a desired gas can be supplied to the lamp chamber L. In this example, as shown in the drawing, the atmosphere in the lamp chamber L is a nitrogen gas atmosphere in which a nitrogen gas (N ₂ ) atmosphere is used. An excimer lamp was used as the ultraviolet lamp 508 of this example. FIG. 19 shows the output wavelength of the excimer lamp.

  As shown in FIG. 19, the excimer lamp used in this example outputs light having a wavelength of about 150 nm to 200 nm. All of the light is in the ultraviolet region, and this light has a short wavelength as ultraviolet light. In addition, the excimer lamp emits almost a single strong emission line. A substantially single strong emission line is as shown in FIG. 19, and in this example, the wavelength is about 172 nm. Ultraviolet light having only a single strong wavelength emission line is referred to herein as single wave ultraviolet light.

  As described above, in this example, ultraviolet irradiation is used as a decomposition process for decomposing the polymer layer 5b. As a specific example, an ultraviolet decomposition process is used, the wafer temperature is set to room temperature (no temperature control), and the atmosphere in the processing chamber S is set. Under an air atmosphere, a single wave ultraviolet ray having a wavelength of 150 nm to 200 nm was irradiated for 10 seconds. FIG. 20 shows the effect of damage recovery for each sample.

  As shown in FIG. 20, the initial dielectric constant (k-value) of the low-k film 5, in this example, the porous MSQ, was 2.38 (Initial).

When the low-k film 5 is etched under the conditions described in the second embodiment, and the photoresist film 6 is oxidized ashing under the same conditions as described in the second embodiment, the porous MSQ Increased to 3.27 (Etch + N ₂ / H ₂ Ash, No LKR).

After the etching and ashing, when the ultraviolet decomposition process described in the second embodiment was performed, the dielectric constant of the porous MSQ further increased to 3.33 (Etch + N ₂ / H ₂ Ash, UV).

However, after the etching and the ashing, the UV decomposition process described in the second embodiment is performed, and the LKR process (conditions are the same as those described in the first embodiment). The dielectric constant of porous MSQ recovered to 2.69 (Etch + N ₂ / H ₂ Ash, UV + LKR).

  Although not shown in FIG. 20, the etching is performed under the conditions described in the second embodiment, and the photoresist film 6 is subjected to the oxidation ashing under the same conditions as described in the second embodiment. After that, when only the LKR process (conditions are the same as those described in the first embodiment), the dielectric constant of the porous MSQ was not recovered. That is, it was almost the same as the dielectric constant of 3.27 when the LKR treatment was not performed.

  As described above, after the decomposition treatment for decomposing the polymer layer 5b is performed on the processed Low-k film 5, as shown in FIG. 16, the reaction gas 10 is used as in the first embodiment. By performing the LKR treatment, the dielectric constant (dielectric constant at this time is assumed to be 3.27) can be improved by about 0.58 compared to the case where the decomposition treatment is not performed.

  As described above, according to the damage recovery method for the low dielectric constant insulating film (Low-k film) according to the second embodiment, the polymer layer generated on the surface of the Low-k film by the processing process is subjected to the ultraviolet decomposition process. After decomposing and decomposing the polymer layer, the damaging functional group generated on the surface of the low dielectric constant insulating film by processing is replaced with a hydrophobic functional group. For this reason, compared with the case where a damage functional group is substituted to a hydrophobic functional group in the state which produced the polymer layer, a damage functional group can be substituted to a hydrophobic functional group better. Since the damage functional group can be better substituted with the hydrophobic functional group, the damage component can be reduced as compared with the state where the polymer layer is formed, and the electrical characteristics of the low dielectric constant insulating film itself can be sufficiently restored.

  Further, since the damaging functional group is better substituted with the hydrophobic functional group, the surface of the processed Low-k film can be made hydrophobic. For this reason, compared with the case where the surface of the Low-k film remains hydrophilic, the cleaning agent can be more sufficiently removed during the wet cleaning. If the cleaning agent can be sufficiently removed, the cause of pattern defects can be reduced and the occurrence of pattern defects can be suppressed.

Furthermore, since the damage recovery method involves a heat treatment for heating the substrate, moisture adsorbed on the damaged layer of the low dielectric constant insulating film, particularly H ₂ O, can be removed, and the metal caused by the adsorbed moisture Oxidation can also be prevented.

  As described above, according to the damage recovery method for the low dielectric constant insulating film according to the second embodiment, the electrical conductivity of the low dielectric constant insulating film itself is suppressed while suppressing the oxidation of the embedded metal and the generation of pattern defects. The characteristics can be fully recovered.

  If a semiconductor device is manufactured using such a damage recovery method, the manufactured semiconductor device can include, for example, an interlayer insulating film with a sufficiently low dielectric constant, as in the first embodiment. A high-performance semiconductor integrated circuit having a high signal transmission speed can be obtained.

  Moreover, since the occurrence of pattern defects is suppressed, the high-performance semiconductor integrated circuit can be manufactured with a high yield.

  Furthermore, since the amount of adsorbed moisture in the interlayer insulating film is reduced, the oxidation of the metal wiring embedded in the interlayer insulating film is also suppressed. By suppressing the oxidation of the metal wiring, it is possible to extend the life of the high-performance semiconductor integrated circuit.

(Third embodiment)
FIG. 21 is a flowchart showing a basic flow of a damage recovery method for a low dielectric constant insulating film (Low-k film) according to the third embodiment of the present invention.

  The third embodiment is a combination of the first embodiment and the second embodiment, and the Low-k film damage recovery method basically follows the following flow.

  First, ST. As shown at 31, the low-k film is processed. During this processing, a polymer layer is formed on the surface of the low-k film, and a damaged layer containing a damaging functional group is formed.

  Next, ST. As shown in FIG. 32, ST. The polymer layer generated by the processing shown in 31 is decomposed by the decomposition method described in the second embodiment.

  Next, ST. As shown in FIG. 33, after decomposing the polymer layer, ST. The damaging functional group generated by the processing shown in 31 is substituted with a hydrophobic functional group.

  Next, ST. As shown in FIG. 34, ST. The damage component existing under the dense layer generated by the replacement process shown in 33 is recovered.

  As described above, the first embodiment and the second embodiment can be combined.

  When the first embodiment and the second embodiment are combined as in the third embodiment, the advantage obtained by the first embodiment and the advantage obtained by the second embodiment And can be obtained together.

  Although not particularly shown, it goes without saying that the semiconductor device can be manufactured by using the damage recovery method for the low dielectric constant insulating film according to the third embodiment.

  Although the present invention has been described according to the first to third embodiments, the present invention is not limited to the first to third embodiments, and various modifications can be made.

  For example, in the first to third embodiments, the damage recovery method for a low dielectric constant insulating film according to the present invention is performed using a through hole (via hole or contact) in an interlayer insulating film using the low dielectric constant insulating film. Although an example of application to the formation of holes) has been shown, the damage recovery method is not only applied to the formation of through holes. For example, the present invention can be applied to the formation of a damascene wiring groove in an interlayer insulating film using a low dielectric constant insulating film.

  Furthermore, since the damage recovery method according to the present invention can suppress the occurrence of pattern defects and can sufficiently recover the electrical characteristics of the low dielectric constant insulating film itself, the damage recovery method is not limited to the damascene wiring grooves and through holes. It can also be applied to processing of a low dielectric constant insulating film.

In the first to third embodiments, MSQ or porous MSQ is used as the low dielectric constant insulating film (Low-k film). However, any insulating film having a lower dielectric constant than the inorganic silicon oxide film may be used. For example, an organic insulating film including a substituent that substitutes a part of the main bond with another bond that lowers the dielectric constant k can be preferably used. An example of the organic insulating film is an organic silicon oxide film. As the organic silicon oxide film, in addition to MSQ or porous MSQ, for example, a methyl group (—CH ₃ ) is introduced into the “Si—O” bond. In addition, a SiOC-based film in which “Si—O” bonds and “Si—CH ₃ ” bonds are mixed can also be used.

In the first to third embodiments, TMSDMA (Trimethylsilyldimethylamine) is used as a reaction gas used in the LKR process, but the reaction gas has a bond between Si and an alkyl group (—C _n H _{2n + 1} ). Any gas can be used. Examples of alkyl groups, for example, there may be mentioned a methyl group (-CH _3), as a gas having a bond of Si and a methyl group, other TMSDMA,
TMMAS (Trimethylmethylaminosilane),
TMICS (Trimethyl (isocyanato) silane),
TMSA (Trimethylsilylacetylene),
TMSC (Trimethylsilylcyanide),
DMSDMA (Dimethylsilyldimethylamine),
HMDS (Hexamethyldisilazane),
TMDS (1,1,3,3-Tetramethyldisilazane),
TMSPyrole (1-Trimethylsilylpyrole),
BSTFA (N, O-Bis (trimethylsilyl) trifluoroacetamide), BDDMMS (Bis (dimethylamino) dimethylsilane) and the like can also be used.

  In addition, the first to third embodiments can be variously modified without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Interlayer insulating film, 3 ... Groove, 4 ... Wiring, 5 ... Low dielectric constant insulating film (Low-k film), 5a ... Dense layer, 5b ... Polymer layer, 6 ... Photoresist film, 9 ... damage components, 10 ... reactive gas, 100 ... semiconductor substrate

Claims (10)

A method for recovering damage of a low dielectric constant insulating film that recovers damage caused to a low dielectric constant insulating film made of an insulating film having a dielectric constant lower than that of an inorganic silicon oxide film,
Processing the low dielectric constant insulating film,
After processing the low dielectric constant insulating film, the damage functional group generated by the processing on the surface of the low dielectric constant insulating film is replaced with a hydrophobic functional group,
A damage recovery method for a low dielectric constant insulating film, comprising recovering damage components existing under the dense layer produced by the substitution treatment on the surface of the low dielectric constant insulating film by using an ultraviolet heat treatment.   2. The low dielectric constant according to claim 1, wherein the low dielectric constant insulating film is an organic insulating film including a substituent that replaces a part of the main bond with another bond that lowers the dielectric constant k. Insulation film damage recovery method. The process of replacing the damaging functional group with a hydrophobic functional group is a process of supplying a reactive gas having a bond of Si and CH ₃ into the processing chamber,
The reaction gas is
TMSDMA (Trimethylsilyldimethylamine),
TMMAS (Trimethylmethylaminosilane),
TMICS (Trimethyl (isocyanato) silane),
TMSA (Trimethylsilylacetylene),
TMSC (Trimethylsilylcyanide)
DMSDMA (Dimethylsilyldimethylamine),
HMDS (Hexamethyldisilazane),
TMDS (1,1,3,3-Tetramethyldisilazane),
TMSPyrole (1-Trimethylsilylpyrole),
3. The low dielectric constant insulation according to claim 1, wherein the dielectric constant insulation is at least one selected from BSTFA (N, O-Bis (trimethylsilyl) trifluoroacetamide) and BDDMDS (Bis (dimethylamino) dimethylsilane). How to recover film damage.   4. The method for recovering damage to a low dielectric constant insulating film according to claim 1, wherein broad-wave ultraviolet light having a wavelength of 200 nm to 380 nm is used for the ultraviolet heat treatment. 5. . The processing of the low dielectric constant insulating film includes a step of etching the low dielectric constant insulating film using a photoresist film as a mask,
5. The damage recovery method for a low dielectric constant insulating film according to claim 1, wherein the photoresist film is ashed after etching the low dielectric constant insulating film. Forming a low dielectric constant insulating film made of an insulating film having a dielectric constant lower than that of the inorganic silicon oxide film on the semiconductor substrate;
Processing the low dielectric constant insulating film and forming a predetermined pattern on the low dielectric constant insulating film;
After processing the low dielectric constant insulating film, replacing the damaging functional group generated on the surface of the low dielectric constant insulating film in the processing step with a hydrophobic functional group;
A step of recovering the damage component existing under the dense layer generated on the surface of the low dielectric constant insulating film in the replacement step by using an ultraviolet heat treatment;
A method for manufacturing a semiconductor device, comprising:   The semiconductor device according to claim 6, wherein the low dielectric constant insulating film is an organic insulating film including a substituent that replaces a part of the main bond with another bond that lowers the dielectric constant k. Production method. The process of replacing the damaging functional group with a hydrophobic functional group is a process of supplying a reactive gas having a bond of Si and CH ₃ into the processing chamber,
The reaction gas is
TMSDMA (Trimethylsilyldimethylamine),
TMMAS (Trimethylmethylaminosilane),
TMICS (Trimethyl (isocyanato) silane),
TMSA (Trimethylsilylacetylene),
TMSC (Trimethylsilylcyanide)
DMSDMA (Dimethylsilyldimethylamine),
HMDS (Hexamethyldisilazane),
TMDS (1,1,3,3-Tetramethyldisilazane),
TMSPyrole (1-Trimethylsilylpyrole),
8. The manufacturing method of a semiconductor device according to claim 6, wherein the semiconductor device is at least one selected from BSTFA (N, O-Bis (trimethylsilyl) trifluoroacetamide) and BDDMDS (Bis (dimethylamino) dimethylsilane). Method.   9. The method of manufacturing a semiconductor device according to claim 6, wherein broad-wave ultraviolet rays having a wavelength of 200 nm to 380 nm are used for the ultraviolet heat treatment. The step of processing the low dielectric constant insulating film and forming a predetermined pattern on the low dielectric constant insulating film includes the step of etching the low dielectric constant insulating film using a photoresist film as a mask,
The method for recovering damage to a low dielectric constant insulating film according to any one of claims 6 to 9, wherein the photoresist film is ashed after the low dielectric constant insulating film is etched.

Images