JP2009158909A - Processing condition inspection and optimization method of damage recovery processing, damage recovering system and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing condition inspection method of damage recovery processing in which process recognition can be performed merely through the damage recovery processing and a change in processing conditions can be detected with high sensitivity. <P>SOLUTION: The processing condition inspection method of the damage recovery processing for reforming an OH group of a Low-k film damaged due to etching and ashing by using a processing gas includes steps of: preparing a substrate having an OH group containing a photoresist film, measuring an initial film thickness of the photoresist film, performing silylation processing as damage recovery processing on the substrate after measuring the initial film thickness, measuring a film thickness of the photoresist film after the silylation processing, calculating a film thickness difference of the photoresist film before and after the silylation processing, and determining whether processing conditions of the silylation processing are appropriate or inappropriate on the basis of the film thickness difference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides, for example, damage recovery processing for a film in which OH groups are present on the surface due to etching or ashing damage such as a low dielectric constant film used as an interlayer insulating film in a semiconductor device formed by a damascene method. The present invention relates to a processing condition inspection method, a processing condition optimization method, a damage recovery processing system, and a storage medium.

  In a semiconductor device manufacturing process, a dual damascene method is frequently used to form wiring grooves or connection holes (see, for example, Patent Document 1).

  On the other hand, with the miniaturization of semiconductor devices, the parasitic capacitance of interlayer insulation films has become an important factor in improving wiring performance. Low dielectric constants made of low dielectric constant materials are used as interlayer insulation films. A film (Low-k film) is being used. As a material constituting the Low-k film, a material having an alkyl group such as a methyl group as a terminal group is generally used.

  However, in the conventional damascene process as described above, the low-k film is damaged during etching and resist film removal (ashing). Such damage causes an increase in the dielectric constant of the low-k film, and the effect of using the low-k film as an interlayer insulating film is impaired.

  As a technique for recovering this type of damage, Patent Document 2 proposes to perform a silylation treatment after etching or removing a resist film. In this silylation treatment, the surface of the portion where the terminal group has become —OH group due to damage is modified with a silylating agent, and an alkyl group such as a methyl group is used as a terminal group.

  When such damage recovery processing is introduced into a mass production system, a process confirmation method is required to determine whether or not the apparatus is normal by setting up the chamber of the silylation processing apparatus or performing a daily check. At present, the low-k film wafer is subjected to etching treatment and ashing treatment, and then the silylation-treated sample is subjected to dilute hydrofluoric acid treatment, and CD and film thickness t before and after dilute hydrofluoric acid treatment are measured to obtain ΔCD and The process is confirmed by grasping Δt.

  However, when confirming the process using such a method, it is necessary to prepare a sample by performing etching and ashing before the silylation treatment. Process confirmation cannot be performed. That is, even if there is a problem with ΔCD or Δt, it cannot be determined whether it is a silylation problem or an etching or ashing problem.

Further, even if the silylation conditions such as gas concentration are different, there is almost no difference in ΔCD and Δt by dilute hydrofluoric acid treatment, and even if equivalent ΔCD and Δt are obtained by dilute hydrofluoric acid treatment, it will be used for subsequent electrical property evaluation. There may be a difference. As described above, in the silylation treatment, a sufficient process confirmation cannot be performed at present.
JP 2002-083869 A JP 2006-049798 A

The present invention has been made in view of such circumstances, and it is possible to perform a process confirmation by a damage recovery process alone and to detect a process condition shift with high sensitivity. It is another object of the present invention to provide a processing condition optimization method.
It is another object of the present invention to provide a damage recovery processing system capable of performing these methods, and a storage medium storing a program for performing such methods.

In order to solve the above-described problem, in the first aspect of the present invention, a damage recovery process for modifying a OH group portion with a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined process. The processing condition inspection method of
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
There is provided a method for inspecting a treatment condition for a damage recovery process including a step of determining whether or not the process condition for the damage recovery process is appropriate based on the film thickness difference.

According to a second aspect of the present invention, there is provided a processing condition optimization method for damage recovery processing in which a OH group portion is modified by a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined processing. And
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
The relationship between the processing conditions and the film thickness difference is obtained in advance, and based on the obtained film thickness difference, the film thickness difference of the OH group-containing resin film before and after the damage recovery process corresponds to the optimum processing condition. There is provided a processing condition optimization method for damage recovery processing including a step of adjusting processing conditions so as to obtain a value to be processed.

  In the first and second aspects, examples of the film in which OH groups are present due to the damage include a low dielectric constant interlayer insulating film. Examples of the OH group-containing resin film include a photoresist film containing an OH group. In this case, a KrF resist film is preferable as the photoresist film containing the OH group. Furthermore, the film thickness of the OH group-containing resin film after the damage recovery process may be thicker than the initial film thickness due to the reaction of the processing gas. Furthermore, the damage recovery process can be performed by a silylation process using a silylating agent as a processing gas. Furthermore, the predetermined treatment that causes the damage may include etching and / or ashing.

  In the said 2nd viewpoint, when performing the said damage recovery process by the silylation process which used the silylating agent as process gas, it is preferable to perform at the temperature of the range of 120-350 degreeC. Further, it is preferable that the gas pressure during the treatment is in the range of 1 to 50 Torr (133 to 6666 Pa).

In a third aspect of the present invention, a damage recovery processing device that modifies an OH group portion with a processing gas with respect to a film that is damaged by a predetermined process and becomes OH groups,
A film thickness measuring device for measuring the film thickness of a predetermined film;
The substrate on which the OH group-containing resin film is formed is carried into the film thickness measuring device, the initial film thickness of the OH group-containing resin film is measured, and the damage recovery processing device is used to recover the damage of the substrate after the initial film thickness measurement. Process, let the film thickness measurement device measure the film thickness of the OH group-containing resin film after the damage recovery process, to determine the film thickness difference of the OH group-containing resin film before and after the damage recovery process, There is provided a damage recovery processing system including control means for determining whether or not the processing conditions of the damage recovery processing are appropriate based on the film thickness difference.

In a fourth aspect of the present invention, a damage recovery processing device for modifying an OH group portion with a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined process;
A film thickness measuring device for measuring the film thickness of a predetermined film;
The substrate on which the OH group-containing resin film is formed is carried into the film thickness measuring device, the initial film thickness of the OH group-containing resin film is measured, and the damage recovery processing device is used to recover the damage of the substrate after the initial film thickness measurement. The film thickness measurement device is made to measure the film thickness of the OH group-containing resin film after the damage recovery process, and the relationship between the processing conditions and the film thickness difference is obtained in advance, and the obtained A damage recovery process including control means for adjusting the processing conditions so that the film thickness difference between the OH group-containing resin films before and after the damage recovery process becomes a value corresponding to the optimal processing conditions based on the film thickness difference Provide a system.

According to a fifth aspect of the present invention, there is provided a damage recovery processing apparatus that operates on a computer and modifies an OH group portion by a processing gas with respect to a film that is damaged by a predetermined process so that OH groups exist. A storage medium storing a program for controlling a damage recovery processing system including a film thickness measuring device for measuring a film thickness of a predetermined film,
The program, when executed,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
A memory for controlling the damage recovery processing system to perform a processing condition inspection method for damage recovery processing including a step of determining whether or not processing conditions for the damage recovery processing are appropriate based on the film thickness difference. Provide media.

According to a sixth aspect of the present invention, there is provided a damage recovery processing apparatus that operates on a computer and modifies an OH group portion by a processing gas with respect to a film that is damaged by a predetermined process so that OH groups exist. A storage medium storing a program for controlling a damage recovery processing system including a film thickness measuring device for measuring a film thickness of a predetermined film,
The program, when executed,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring an initial film thickness of the OH group-containing resin film;
A step of performing damage recovery processing on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
The relationship between the processing conditions and the film thickness difference is obtained in advance, and based on the obtained film thickness difference, the film thickness difference of the OH group-containing resin film before and after the damage recovery process corresponds to the optimum processing condition. There is provided a storage medium characterized by controlling the damage recovery processing system so that a damage recovery processing condition optimization method including a step of adjusting a processing condition so as to achieve a value to be performed.

The inventors of the present invention stated that "Damage that the Low-k film undergoes during etching and ashing is due to the formation of OH groups, and the damage recovery process represented by silylation treatment modifies this OH group part. As a result of repeated examinations focusing on the point that `` there is a thing to do '', prior to the damage recovery processing of the actual substrate, damage recovery processing is performed on the substrate on which the OH group-containing resin film is formed, It has been found that the processing conditions can be easily and accurately confirmed by determining the difference in film thickness between the front and rear OH group-containing resin films.
In other words, by performing damage recovery processing on the substrate on which the OH group-containing resin film is formed in this way, it is not necessary to perform damage manifestation processing such as etching or ashing before the damage recovery processing. It is simple and the process confirmation can be performed by the damage processing alone. In addition, the film thickness difference of the OH group-containing resin film changes with high sensitivity according to changes in processing conditions. Therefore, the processing conditions can be confirmed easily and accurately.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a silylation processing system capable of implementing the method of the present invention.

  The silylation processing system 100 performs a silylation process as a damage recovery process on a low-k film formed as an interlayer insulating film on a semiconductor wafer (hereinafter simply referred to as a wafer) that is a substrate to be processed. A silylation processing apparatus 1 that performs processing, a film thickness measuring apparatus 2 that measures the film thickness of a photoresist formed on an inspection wafer used in the processing condition inspection of this embodiment, and a carrier that stores a plurality of wafers W It has a loader 3 to be placed, a transfer device 4 for transferring the wafer W, and a control unit 5 for controlling these components.

  The control unit 5 includes a controller 6 having a microprocessor (computer) connected to and controlled by the silylation processing apparatus 1, the film thickness measurement apparatus 2, the loader 3, and the transfer apparatus 4. ing. Connected to the controller 6 is a user interface 7 including a keyboard for an operator to input commands and the like for managing the silylation processing system 100, and a display for visualizing and displaying the operating status of the silylation processing system. ing. Further, the controller 6 stores a control program for controlling the control target of each component of the silylation processing system 100 and a program for storing the silylation processing system 100 to perform a predetermined process, that is, a recipe. Part 8 is connected. The recipe is stored in a storage medium in the storage unit 8. The storage medium may be a fixed medium such as a hard disk or a portable medium such as a CDROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example. If necessary, a predetermined process is performed under the control of the controller 6 by calling an arbitrary recipe from the storage unit 8 according to an instruction from the user interface 7 and causing the controller 6 to execute the recipe.

  As the silylation processing apparatus 1 which is the damage recovery processing apparatus, the one having the structure shown in the schematic sectional view of FIG. 2 can be used. The silylation processing apparatus 1 includes a chamber 21 that accommodates a wafer W, and a wafer mounting table 22 is provided below the chamber 21. A heater 23 is embedded in the wafer mounting table 22 so that the wafer W mounted thereon can be heated to a desired temperature. Wafer lift pins 24 are provided on the wafer mounting table 22 so as to protrude and retract, and the wafer W can be positioned at a predetermined position spaced upward from the wafer mounting table 22 when the wafer W is loaded and unloaded. It has become.

An internal container 25 is provided in the chamber 21 so as to partition a narrow processing space S including the wafer W, and a silylating agent (silylation gas) is supplied to the processing space S. . A gas introduction path 26 extending vertically is formed in the center of the inner container 25.

A gas supply pipe 27 is connected to the upper part of the gas introduction path 26, and TMSDMA (N-Trimethylsilyldimethylamine), DMSDMA (Dimethylsilyldimethylamine), TMDS (1,1,3,3-Tetramethyldisilazane) is connected to the upper part of the gas introduction path 26. ), TMSpyrole (1-Trimethylsilylpyrole), BSTFA (N, O-Bis (trimethylsilyl) trifluoroacetamide), BDDMMS (Bis (dimethylamino) dimethylsilane) and other silylating agent supply source 28 for supplying a silylating agent, A pipe 31 extending from a carrier gas supply source 30 for supplying a carrier gas made of Ar, N ₂ gas or the like is connected. The pipe 29 is provided with a vaporizer 32, a mass flow controller 33, and an open / close valve 34 for vaporizing the silylating agent in order from the silylating agent supply source 28 side. On the other hand, the mass flow controller 35 and the opening / closing valve 36 are provided in the piping 31 in order from the carrier gas supply source 30 side. Then, the silylating agent vaporized by the vaporizer 32 is carried by the carrier gas and introduced into the processing space S surrounded by the inner vessel 25 through the gas supply pipe 27 and the gas introduction path 26. During processing, the wafer W is heated to a predetermined temperature by the heater 23. In this case, the wafer temperature can be controlled from room temperature to 300 ° C., for example.

  An air introduction pipe 37 is provided so as to extend from the air atmosphere outside the chamber 21 into the internal container 25 inside the chamber 21. The atmosphere introduction pipe 37 is provided with a valve 38. By opening the valve 38, the atmosphere is introduced into the processing space S surrounded by the inner container 25 in the chamber 21, thereby supplying moisture and silylation. The reaction can be promoted.

  A gate valve G is provided on the side wall of the chamber 21, and the wafer W is loaded and unloaded by opening the gate valve G. A load lock chamber (not shown) is provided across the gate valve G, and the wafer is transferred to the load lock chamber held in the atmosphere by the transfer device 4 in the atmosphere, and the load lock chamber is evacuated. After that, the wafer W is carried into the chamber 21 by a transfer device (not shown) provided in the load lock chamber. When the wafer W is unloaded, the reverse operation is performed.

  An exhaust pipe 40 is provided at the peripheral edge of the bottom of the chamber 21, and the inside of the chamber 21 can be exhausted through the exhaust pipe 40 by a vacuum pump (not shown) so as to be controlled to a predetermined pressure. Yes. A cold trap 41 is provided in the exhaust pipe 40. Further, a baffle plate 42 is provided in a portion between the wafer mounting table 22 and the upper chamber wall.

  The film thickness measuring device 2 may be any film thickness measuring device that is normally used in this field. For example, a film thickness measuring device provided with a commercially available reflection spectral film thickness meter can be suitably used.

  The silylation treatment of the actual wafer is carried out by damaging the low-k film when etching and ashing is performed on the wafer on which the low-k film is formed as an interlayer insulating film. Specifically, the OH group generated in the Low-k film due to damage is replaced with a silyl group such as a trimethylsilyl group for modification, thereby restoring electrical characteristics and the like.

In the present embodiment, the processing conditions of the silylation processing apparatus are confirmed prior to the processing of the actual wafer, which will be described in detail below.
The confirmation of the processing conditions of the silylation processing apparatus needs to be understood by actually performing the silylation process. However, as described above, the silylation process as the damage recovery process has an OH group due to etching and ashing damage. When generated, the OH group is substituted with a silyl group. Since the low-k film does not have an OH group in the initial state and no silylation reaction occurs, conventionally, a low-k film is used. A sample in which the formed wafer is subjected to etching and ashing to generate OH groups is subjected to silylation treatment, and then processed by dilute hydrofluoric acid treatment to detect CD change or film thickness change of the Low-k film. The conditions were being confirmed.
However, when confirming the processing conditions in this way, the sample making is complicated, the processing conditions in the silylation process cannot be confirmed independently, and the sensitivity is not sufficient. It was.
On the other hand, in the present embodiment, a wafer on which a photoresist film containing an OH group is formed is subjected to silylation treatment, and the film thickness difference of the film is obtained, thereby easily and accurately confirming the processing conditions. Do.

FIG. 3 is a flowchart showing a processing condition inspection method of the silylation processing apparatus of this embodiment using the silylation processing system.
First, a loader 3 is prepared in a state where an inspection wafer on which a photoresist film containing an OH group is formed is housed in a carrier (step 1). Examples of the photoresist film containing an OH group include a g-line resist film and a KrF resist film.

  Next, a wafer for inspection is taken out from the carrier on the loader 3 by the transfer device 4 and transferred to the film thickness measuring device 2, where the film thickness of the photoresist film containing OH groups is measured (step 2).

Next, the inspection wafer is transferred to the silylation processing apparatus 1 by the transfer device 4, and the inspection wafer is subjected to silylation processing as damage recovery processing (step 3). In order to carry the inspection wafer into the silylation processing apparatus 1, the wafer is first transferred to a load lock chamber (not shown), pressure adjustment is performed there, and then the inside of the chamber 21 is transferred by a transfer device (not shown) in the load lock chamber. It is done by carrying in.
At this time, conditions for the silylation treatment, such as treatment time, pressure, concentration of silylation gas, temperature, and the like are set based on a predetermined recipe for actual wafer treatment. The reaction between the photoresist film and the silylating agent at this time is shown below, taking a case where a g-line resist film is used as the photoresist film and TMSDMA is used as the silylating agent (silylating gas) as an example. As shown in the formula, a silylation reaction occurs, and the film thickness of the photoresist film increases.

  After the silylation treatment, the inspection wafer is returned from the chamber 1 to the load lock chamber, opened to the atmosphere, and then transferred to the film thickness measurement device 2 by the transfer device 4, and a photoresist containing OH groups after the silylation treatment. The film thickness is measured (step 4).

  Next, a difference in film thickness between the initial film thickness of the photoresist film obtained in step 2 and the film thickness of the photoresist film after silylation treatment obtained in step 4 (after silylation treatment) is calculated by the calculation unit of the controller 6. (Thickness increase amount) Δt is obtained (step 5).

  Then, it is determined whether or not the film thickness difference Δt is within an allowable range (step 6). Thereby, it can be confirmed whether the processing conditions in the silylation processing apparatus 1 are appropriate.

  As a result, if the film thickness difference Δt is within the allowable range, the silylation process for the actual wafer is started (step 7). If Δt is outside the allowable range, the conditions are adjusted (step 8), and then the silylation process is performed. To start.

  The above inspection process can be controlled by the control unit 5 as follows. After preparing the inspection wafer in the carrier in step 1 in step 1, the loader 3 is prepared, and the transfer device 4 is controlled to transfer the inspection wafer to the film thickness measuring device 2, and the photoresist measured in step 2 is measured. The film thickness is transmitted to the controller 6. After the silylation process, the transfer apparatus 4 is controlled to transfer the inspection wafer to the film thickness measuring apparatus 2, and the film thickness of the photoresist film after the silylation process measured in step 4 is transmitted to the controller 6. The calculation unit of the controller 6 calculates the film thickness difference Δt in step 5 based on these data, and compares the value of Δt with the film thickness difference corresponding to the normal silylation process conditions set in advance. Thus, it is determined whether or not Δt in step 6 is within an allowable range, and the result is displayed on the display of the user interface 7, for example. Further, when Δt is out of the allowable range, an alarm notifying the abnormality can be activated. In addition, adjustment of processing conditions when it is determined to be abnormal can be performed by a command from the controller 6.

  As described above, in a photoresist film containing an OH group such as a g-line resist film or a KrF resist film, a silylation reaction occurs between the OH group and a silylating agent (silylation gas). The film thickness is increased by substituting silyl groups. In the low-k film, when the silylation reaction occurs, the amount of increase in the film thickness is extremely small. On the other hand, the photoresist film containing the OH group has a large film thickness change, and the difference in the silylation process conditions. Therefore, it is possible to determine whether or not the silylation conditions are appropriate by obtaining this film thickness difference Δt. That is, the progress of the silylation reaction varies depending on the conditions of the silylation treatment, which is reflected with high accuracy and good reproducibility as the film thickness difference Δt before and after the silylation treatment of the photoresist film, and the film thickness difference Δt is appropriate. If it is within this range, the silylation treatment conditions are normal, and if it is outside this range, it can be determined that the silylation treatment conditions are abnormal.

  Next, the result of actually confirming the change in film thickness when such a photoresist film containing OH groups is subjected to silylation will be described.

  FIG. 4 shows the result of obtaining the film thickness increase amount (film thickness difference) Δt when the silylation process is performed on a wafer on which a G-line resist film and a KrF resist film are formed as a photoresist film containing an OH group. FIG. Here, the silylation treatment was performed under the conditions of chamber internal pressure: 50 Torr (6666 Pa), silylating agent: TMSDMA, flow rate: 500 sccm (mL / min), stage temperature: 180 ° C., treatment time: 150 sec. Moreover, as a film thickness measuring apparatus, the optical interference type film thickness measuring device (brand name: Nano Spec 8300) was used (and so on). As shown in FIG. 4, in the G-line resist film, the average value of the film thickness increase Δt is 437 nm, and in the KrF resist film, the average value of the film thickness increase Δt is 192 nm. It was confirmed that In addition, the same silylation treatment was performed on wafers of different lots, but all of the results were equivalent and confirmed to be reproducible. Both variations were within ± 5%, but it was confirmed that the KrF resist film had less variation. Considering this point, it can be judged that the KrF resist film is more advantageous. In determining Δt, the resist film was heated during the silylation treatment, and the resist film contracted (shrinked). Therefore, Δt was determined in consideration of the contraction. That is, Δt is a value obtained by adding a value contracted by heating to a value obtained by subtracting the initial film thickness from the film thickness after silylation. The same applies to the following.

Next, it was grasped whether or not it was possible to detect when the concentration of the silylating agent was changed. The result is shown in FIG. FIG. 5 shows an increase in film thickness (film thickness difference) Δt when a silylation treatment is performed by changing the concentration of the silylating agent on a wafer on which a KrF resist film is formed as a photoresist film containing OH groups. It is a figure which shows a result. Here, chamber pressure: 50 Torr (6666 Pa), stage temperature: 180 ° C., processing time: 150 sec, common conditions, TMSDMA alone supplied at a flow rate of 500 sccm (mL / min) (TMSDMA 100%) Then, TMSDMA and N ₂ gas were flowed at a flow rate of 40 sccm (mL / min) and 4000 sccm (mL / min), respectively, and diluted and supplied (TMSDMA 1%). As shown in FIG. 5, the average value of Δt when TMSDMA was 100% was 248 nm, whereas the average value of Δt when TMSDMA was 1% was 122 nm. It was confirmed that there was a difference in (thickness difference) Δt. From this, it was confirmed that when there is a problem in the gas supply system of the silylation processing apparatus, this can be detected from the difference in the film thickness increase amount (film thickness difference) Δt.

Next, by changing the dilution rate of the silylating agent as the silylation condition, the change in the film thickness increase (film thickness difference) Δt of the KrF resist film and the actual silylation treatment of the Low-k film We grasped the change in the amount of electrical capacity recovery. The result is shown in FIG. In FIG. 6, the horizontal axis represents the TMSDMA concentration (dilution ratio), and the vertical axis represents the KrF resist film thickness increase (film thickness difference) Δt and the low-k film capacity recovery amount. FIG. Here, the chamber internal pressure: 20 Torr (2666 Pa), the stage temperature: 180 ° C., the processing time: 30 sec are used as common conditions, TMSDMA is used as the silylating agent, and the TMSDMA / N ₂ flow rate is 80/4000 sccm (mL / min). , 40/4000 sccm (mL / min), 20/4000 sccm (mL / min) (TMSDMA concentrations are 0.2%, 0.4%, and 0.8%, respectively) for silylation treatment. It was. As shown in FIG. 6, the tendency of the film thickness increase amount (film thickness difference) Δt of the KrF resist film coincides with the tendency of the capacity recovery amount. From the thickness difference (Δt), it was found that the capacity recovery effect (damage recovery effect) by the silylation treatment under the conditions can be confirmed. That is, it was understood that the damage recovery effect by the silylation treatment increases as the value of Δt increases.

  Next, the change of the increase amount (film thickness difference) Δt of the KrF resist film when various silylation treatment conditions were changed was grasped. The result is shown in FIG. 7A shows the relationship between silylation treatment time and Δt, FIG. 7B shows the relationship between chamber pressure and Δt, and FIG. 7C shows the concentration (dilution ratio) of the silylating agent (TMSDMA). (D) shows the relationship between temperature and Δt. Among these, as shown in (a), (c), and (d), with respect to time, silylating agent concentration, and temperature, Δt increases as they increase, and during the silylation treatment, It was confirmed that the damage recovery effect increased with increasing time, silylating agent concentration and temperature. As for the concentration of TMSDMA, the value of Δt is equivalent to 10% without dilution (TMSDMA 100%), so that the damage recovery effect is not different from that without dilution if diluted to 10%. I understand. That is, since the effect is saturated even if TMSDMA reaches 10% or more, it is preferable to dilute TMSDMA to 10% in consideration of cost.

As shown in (b), it can be seen that the value of Δt does not change even if the pressure in the chamber increases. However, here, the pressure of TMSDMA is constant and the pressure is adjusted with N ₂ gas, and the molecular weight of TMSDMA is the same at each pressure. From this, the molecular weight of the silylating agent increases as the pressure increases. If it is increased, Δt is expected to increase.

  From the above results, the film thickness increase (thickness difference) Δt when the OH group-containing photoresist film is subjected to the silylation treatment reflects the change in the silylation treatment conditions. By measuring Δt, the silylation treatment is performed. It was confirmed that the suitability of the conditions can be grasped. In addition, since the tendency of change in Δt with the change in silylation treatment condition is consistent with the tendency of change in the capacity recovery amount of the low-k film, the film when the photoresist film containing OH group is subjected to silylation treatment. It is also possible to optimize the processing conditions of the silylation process, which is a damage recovery process, by using a method for obtaining a thickness increase (film thickness difference) Δt.

  In such optimization of the processing conditions, the relationship between each processing condition and Δt is stored in the storage unit 8 of the control unit 5 in advance, and silylation is performed on the inspection wafer under the initial conditions to obtain Δt. Based on the Δt, the silylation treatment conditions can be adjusted so that the film thickness difference becomes a value corresponding to the optimum silylation conditions.

  By the way, the silylation treatment conditions have not been optimized by comprehensively considering the reactivity, throughput, device characteristics, etc. with respect to temperature, pressure, etc. As a result, it was difficult to achieve the highest reaction amount at the lowest chemical cost.

Hereinafter, optimization of the conditions for the silylation treatment based on such a viewpoint will be described.
First, with regard to the silylation treatment temperature, it has been found that an increase in the film thickness of a photoresist film containing OH groups occurs at 120 ° C. or higher. On the other hand, the heat resistance temperature of the semiconductor element is about 350 ° C. For this reason, the silylation treatment temperature is preferably in the range of 120 to 350 ° C.

Next, the chamber internal pressure (gas pressure) during the silylation process will be described. Here, a KrF resist is used as a photoresist containing an OH group, TMSDMA is used as a silylating agent (silylation gas), TMSDMA partial pressure: 0.75 Torr (100 Pa), silylation treatment temperature: 180 ° C., total Processing time: Under the condition of 70 sec, the pressure and the KrF resist are changed by changing the pressure in the chamber (N ₂ + TMSDMA pressure) to 1.5 Torr (200 Pa), 5 Torr (667 Pa), 12.5 Torr (1666 Pa), 50 Torr (6666 Pa). The relationship between the film thickness change Δt and the TMSDMA partial pressure change with time were grasped. The result is shown in FIG. FIG. 8A is a diagram showing the relationship between the pressure in the chamber and the change in film thickness of the KrF resist, and FIG. 8B is a diagram showing the change over time in the TMSDMA partial pressure at each pressure. As shown in these figures, when the pressure in the chamber is 1.5 to 12.5 T0rr (200 to 1666 Pa), Δt is relatively high and relatively high reactivity is obtained, and in particular, when t is 5 Torr (667 Pa), Δt is the highest. It can be seen that the largest and highest reaction can be obtained. On the other hand, when the pressure in the chamber is 50 Torr (6666 Pa), the time required for increasing the pressure and evacuation becomes longer, so the time for holding the silylating agent at a predetermined partial pressure becomes shorter and the reaction amount tends to decrease. It turned out to be. Therefore, the pressure in the chamber is preferably 50 Torr (6666 Pa) or less.

  On the other hand, the pressure in the chamber is changed to 0.5 Torr (66.7 Pa), 1.5 Torr (200 Pa), 3 Torr (400 Pa), 5 Torr (667 Pa), 12.5 Torr (1666 Pa), and the wafer is heated to 180 ° C. I grasped the time. The result is shown in FIG. As shown in this figure, since heat transfer is slow at 0.5 Torr (66.7 Pa), it tends to take time to raise the temperature. On the other hand, such a tendency is small if it is 1.5 Torr (200 Pa) or more, and it is considered that even if it is 1.5 Torr or less. Considering these points, it can be said that an intermediate value of 1 Torr (133 Pa) or more is preferable. More preferably, it is 1.5 Torr (200 Pa) or more.

Next, a substrate processing system that incorporates a silylation processing system for carrying out the present invention and that can perform etching, ashing, and silylation processing in succession will be described.
Since the silylation treatment as the damage recovery treatment is a treatment carried out after etching and ashing, it is preferable to carry out the treatment continuously without breaking the vacuum after etching and ashing. In consideration of this point, a multi-chamber type substrate processing system capable of continuously performing etching, ashing, and silylation without breaking the vacuum will be described. FIG. 10 is a plan view showing a schematic structure of such a substrate processing system. The substrate processing system 200 processes a semiconductor wafer W (substrate) in which a photoresist film as an etching mask having a predetermined circuit pattern is formed on a Low-k film to be etched by a photolithography process. There are provided etching units 51 and 52 for performing plasma etching, an ashing unit 53 for performing ashing, and a silylation processing unit 54. Each of these units 51 to 54 carries a hexagonal wafer. It is provided corresponding to each of the four sides of the chamber 55. Load lock chambers 56 and 57 are provided on the other two sides of the wafer transfer chamber 55, respectively. A wafer loading / unloading chamber 58 is provided on the opposite side of the load lock chambers 56 and 57 to the wafer transfer chamber 55, and a wafer W can be accommodated on the opposite side of the load locking chambers 56 and 57 of the wafer loading / unloading chamber 58. Ports 59, 60, and 61 for attaching the three carriers C are provided. The silylation processing unit 54 has the same configuration as the main part of the silylation processing apparatus 1 shown in FIG.

  Etching units 51 and 52, ashing unit 53, silylation processing unit 54, and load lock chambers 56 and 57 are connected to each side of wafer transfer chamber 55 via gate valve G, as shown in FIG. These are communicated with the wafer transfer chamber 55 by opening the corresponding gate valve G, and are disconnected from the wafer transfer chamber 55 by closing the corresponding gate valve G. A gate valve G is also provided at a portion connected to the wafer loading / unloading chamber 58 of the load lock chambers 56 and 57, and the load lock chambers 56 and 57 open the corresponding gate valve G to open the wafer loading. The wafer is communicated with the exit chamber 58 and is shut off from the wafer loading / unloading chamber 58 by closing the corresponding gate valve G.

  In the wafer transfer chamber 55, a wafer transfer device 62 that loads and unloads the wafer W with respect to the etching units 51 and 52, the ashing unit 53, the silylation processing unit 54, and the load lock chambers 56 and 57 is provided. . The wafer transfer device 62 is disposed substantially at the center of the wafer transfer chamber 55, and has two blades 64a and 64b that hold the wafer W at the tip of a rotatable / extensible / retractable portion 63 that can rotate and expand / contract. These two blades 64a and 64b are attached to the rotation / extension / contraction section 63 so as to face opposite directions. The wafer transfer chamber 55 is maintained at a predetermined degree of vacuum.

  The three ports 59, 60, 61 for attaching the carrier C in the wafer carry-in / out chamber 58 are configured to directly accommodate the wafer W containing the wafer W or the empty carrier C. (Not shown) is communicated with the wafer loading / unloading chamber 58 while preventing the outside air from entering. An alignment chamber 65 is provided on the side surface of the wafer loading / unloading chamber 58, where the wafer W is aligned. A film thickness measuring device 69 is provided on the opposite side of the wafer carry-in / out chamber 58 from the alignment chamber 65. The film thickness measuring device 69 is configured in the same manner as the film thickness measuring device 2 of FIG.

  In the wafer loading / unloading chamber 58, a wafer transfer device 66 for loading / unloading the wafer W into / from the carrier C and loading / unloading the wafer W into / from the load lock chambers 56, 57 is provided. The wafer transfer device 66 has an articulated arm structure, and can run on the rail 68 along the arrangement direction of the carrier C. The wafer W is placed on the hand 67 at the tip thereof and transferred. I do.

  Each of the above components of the substrate processing system 200 is controlled by the control unit 70. The control unit 70 is configured similarly to the control unit 5 of FIG.

  In such a substrate processing system, when processing an actual wafer, the wafer W taken out from the carrier C is transferred to the wafer transfer chamber 55 held in vacuum via the wafer loading / unloading chamber 58 and the load lock chamber 56 or 57. In the etching unit 51 or 52, the ashing unit 53, and the silylation processing unit 54, a silylation process that is an etching process, an ashing process, and a damage recovery process is sequentially performed without breaking the vacuum. Prior to processing the wafer, the carrier C is attached to one of the ports 59, 60, 61 in a state where the inspection wafer on which the photoresist film containing OH groups is formed is stored in the carrier C, and this inspection wafer is attached. Is transferred to the film thickness measuring device 69 to measure the film thickness, and then the wafer for inspection is loaded into the load lock chamber 5 Or transferred into the silylation treatment unit 54 by the wafer transfer apparatus 62 of the wafer transfer chamber 55 through the 57, it performs the silylation process. Thereafter, the wafer for inspection after the silylation treatment is transferred to the load lock chamber 56 or 57 by the wafer transfer device 62, the wafer for inspection is taken out by the wafer transfer device 66, and is transferred again to the film thickness measuring device 69. The film thickness after the silylation treatment is measured, and then the inspection wafer is returned to the carrier C. This process is performed on one or a plurality of inspection wafers, the amount of increase in film thickness (film thickness difference) Δt due to the silylation process is obtained, and the processing conditions of the silylation processing unit 54 are confirmed as described above. I do.

  The present invention can be variously modified without being limited to the above embodiment. For example, in the above-described embodiment, the case where the present invention is applied to the damage recovery processing of the Low-k film has been described. However, the present invention is not limited to this, and any film can be applied as long as it is damaged and has OH groups. is there. Further, in the above embodiment, the case where the present invention is applied to the treatment for recovering the damage after etching and ashing is shown. However, the present invention is applicable even when these are used alone, and OH groups exist in the recovery target film due to the damage. Any other process such as a wet cleaning process may be used as long as the process is performed. Furthermore, although the G-line resist film and the KrF resist have been described as examples of the photoresist film containing OH groups in the above embodiment, the present invention is not limited to this, and the OH group is not limited to the photoresist film. Any resin film can be used.

Furthermore, in the above embodiment, the silylation process has been described as an example of the damage recovery process. However, the present invention is not limited to this, and the reaction is not limited to the silylation process as long as the reaction can replace the OH group with a CH ₃ group or the like. It may be the process.

  Furthermore, in the above-described embodiment, an example in which a semiconductor wafer is used as the substrate to be processed has been described. However, the present invention is not limited to this, and another substrate such as an FPD (flat panel display) substrate may be used.

The block diagram which shows the silylation processing system which can implement the method of this invention. The schematic sectional drawing which shows the silylation processing apparatus contained in the silylation processing system of FIG. The flowchart which shows the processing condition inspection method of the silylation processing apparatus of this embodiment using the silylation processing system of FIG. The figure which shows the result of having calculated | required the film thickness increase amount (film thickness difference) (DELTA) t at the time of performing the silylation process about the wafer which formed the G-line resist film and the KrF resist film as a photoresist film containing OH group. The result of having calculated | required the film thickness increase amount (film thickness difference) (DELTA) t at the time of performing the silylation process by changing the density | concentration of a silylating agent about the wafer which formed the KrF resist film as a photoresist film containing OH group is shown. Figure. The horizontal axis represents the TMSDMA concentration (dilution rate), and the vertical axis represents the KrF resist film thickness increase (film thickness difference) Δt and the low-k film capacity recovery amount, showing the relationship. The figure which shows the relationship between silylation processing time and (DELTA) t, the relationship between chamber pressure and (DELTA) t, the density | concentration (dilution rate) of silylating agent (TMSDMA), and (DELTA) t, and the relationship between temperature and (DELTA) t. The figure which shows the relationship between the process time and TMSDMA partial pressure in each chamber internal pressure in the relationship between chamber internal pressure and (DELTA) t of KrF resist. The figure which shows the temperature rise curve of a wafer in each chamber internal pressure. The top view which shows schematic structure of the substrate processing system which incorporates the silylation processing system for implementing this invention, and can perform an etching, ashing, and a silylation process continuously.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Silylation processing apparatus 2; Film thickness measurement apparatus 3; Loader 4; Conveyance apparatus 5; Control part 6; Controller 7; User interface 8;

Claims (20)

A processing condition inspection method for damage recovery processing, in which an OH group portion is modified by a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined processing,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
A process condition inspection method for damage recovery processing, comprising: determining whether or not the process conditions for damage recovery processing are appropriate based on the film thickness difference.   2. The processing condition inspection method for damage recovery processing according to claim 1, wherein the film in which OH groups are present upon receiving the damage is a low dielectric constant interlayer insulating film.   3. The processing condition inspection method for damage recovery processing according to claim 1, wherein the OH group-containing resin film is a photoresist film containing an OH group. 4.   4. The processing condition inspection method for damage recovery processing according to claim 3, wherein the photoresist film containing an OH group is a KrF resist film.   The film thickness of the said OH group containing resin film after the said damage recovery process becomes thicker than an initial film thickness by reaction of the said process gas, The Claim 1 characterized by the above-mentioned. Processing condition inspection method of damage recovery processing.   6. The processing condition inspection method for damage recovery processing according to claim 1, wherein the damage recovery processing is performed by silylation processing using a silylating agent as a processing gas.   7. The processing condition inspection method for damage recovery processing according to claim 1, wherein the predetermined processing for giving damage is etching and / or ashing. A process condition optimization method for damage recovery processing that modifies an OH group portion with a processing gas to a film in which OH groups are present after being damaged by a predetermined process,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
The relationship between the processing conditions and the film thickness difference is obtained in advance, and based on the obtained film thickness difference, the film thickness difference of the OH group-containing resin film before and after the damage recovery process corresponds to the optimum processing condition. A method for optimizing the processing conditions of damage recovery processing, including a step of adjusting the processing conditions so as to be a value to be processed.   9. The method for optimizing a damage recovery process according to claim 8, wherein the film in which OH groups are present upon receiving the damage is a low dielectric constant interlayer insulating film.   The process condition optimization method for damage recovery processing according to claim 8 or 9, wherein the OH group-containing resin film is a photoresist film containing an OH group.   The method for optimizing a damage recovery process according to claim 10, wherein the photoresist film containing an OH group is a KrF resist film.   The film thickness of the said OH group containing resin film after the said damage recovery process becomes thicker than an initial film thickness by reaction of the said process gas, The any one of Claims 8-11 characterized by the above-mentioned. Process optimization method for damage recovery processing.   The damage recovery processing condition optimization method according to any one of claims 8 to 12, wherein the damage recovery processing is performed by silylation processing using a silylating agent as a processing gas. .   The method for optimizing treatment conditions for damage recovery processing according to claim 13, wherein the silylation treatment is performed at a temperature in a range of 120 to 350 ° C.   15. The process condition optimization method for damage recovery process according to claim 13 or 14, wherein the silylation process is performed in a gas pressure range of 1 to 50 Torr (133 to 6666 Pa) during the process. .   The damage recovery process processing condition optimization method according to any one of claims 8 to 15, wherein the predetermined process for giving damage is etching and / or ashing. A damage recovery processing device for modifying the OH group portion by a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined process;
A film thickness measuring device for measuring the film thickness of a predetermined film;
The substrate on which the OH group-containing resin film is formed is carried into the film thickness measuring device, the initial film thickness of the OH group-containing resin film is measured, and the damage recovery processing device is used to recover the damage of the substrate after the initial film thickness measurement. Process, let the film thickness measurement device measure the film thickness of the OH group-containing resin film after the damage recovery process, to determine the film thickness difference of the OH group-containing resin film before and after the damage recovery process, A damage recovery processing system including control means for determining suitability of processing conditions for the damage recovery processing based on the film thickness difference. A damage recovery processing device for modifying the OH group portion by a processing gas with respect to a film in which OH groups are present after being damaged by a predetermined process;
A film thickness measuring device for measuring the film thickness of a predetermined film;
The substrate on which the OH group-containing resin film is formed is carried into the film thickness measuring device, the initial film thickness of the OH group-containing resin film is measured, and the damage recovery processing device is used to recover the damage of the substrate after the initial film thickness measurement. The film thickness measurement device is made to measure the film thickness of the OH group-containing resin film after the damage recovery process, and the relationship between the processing conditions and the film thickness difference is obtained in advance, and the obtained A damage recovery process including control means for adjusting the processing conditions so that the film thickness difference between the OH group-containing resin films before and after the damage recovery process becomes a value corresponding to the optimal processing conditions based on the film thickness difference system. A damage recovery processing device that operates on a computer and modifies the OH group portion with a processing gas for a film that is damaged by a predetermined process and becomes OH groups, and measures the film thickness of the predetermined film A storage medium storing a program for controlling a damage recovery processing system including a film thickness measuring device.
The program, when executed,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
A memory for controlling the damage recovery processing system to perform a processing condition inspection method for damage recovery processing including a step of determining whether or not processing conditions for the damage recovery processing are appropriate based on the film thickness difference. Medium. A damage recovery processing device that operates on a computer and modifies the OH group portion with a processing gas for a film that is damaged by a predetermined process and becomes OH groups, and measures the film thickness of the predetermined film A storage medium storing a program for controlling a damage recovery processing system including a film thickness measuring device.
The program, when executed,
Preparing a substrate on which an OH group-containing resin film is formed;
Measuring the initial film thickness of the OH group-containing resin film;
A step of performing a damage recovery process on the substrate after the initial film thickness measurement;
Measuring the film thickness of the OH group-containing resin film after the damage recovery treatment;
Obtaining a film thickness difference of the OH group-containing resin film before and after the damage recovery process;
The relationship between the processing conditions and the film thickness difference is obtained in advance, and based on the obtained film thickness difference, the film thickness difference of the OH group-containing resin film before and after the damage recovery process corresponds to the optimum processing condition. A storage medium that controls the damage recovery processing system so as to perform a processing condition optimization method for damage recovery processing including a step of adjusting the processing conditions so as to obtain a value to be satisfied.

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