JP2008109050A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device for suppressing the generation of reaction product residues and photoresist residues. <P>SOLUTION: The manufacturing method of the semiconductor device includes: a process of dry-etching a wiring layer 25 on a semiconductor substrate 21 using a chlorine gas with a photoresist 27 as a mask; and a process of setting the semiconductor substrate 21 having the photoresist 27, the pattern-formed wiring layer 25 and a reaction product 31 to about 100°C lower than the evaporation temperature of the reaction product 31 and the curing temperature of the photoresist 27, exposing it to steam plasma having an H radical and an OH radical, elevating the temperature of the semiconductor substrate 21 while maintaining a first plasma atmosphere thereafter, switching to oxygen plasma having an O radical at about 170°C at which the ashing speed of the photoresist 27 by the O radical rapidly becomes high, elevating it to a temperature not exceeding 250°C while maintaining an oxygen plasma atmosphere thereafter, and removing the reaction product 31 and the photoresist 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device according to an etching technique.

  For the wiring layer of a semiconductor device, a metal film such as AlCu or AlSiCu is often used. These wiring layers are usually formed by selectively etching a metal film formed on an insulating film or the like formed on a semiconductor substrate by dry etching using a photoresist as a mask. The dry etching is performed using, for example, a chlorine (Cl) -based halogen gas.

The dry-etched wiring layer has a reaction product including a chlorine-based gas, for example, AlCl ₃ , Al ₂ Cl ₆ , and the like. When the reaction product is exposed to the atmosphere, it reacts with moisture in the atmosphere to become hydrochloric acid (HCl), which reacts with Al in the wiring and forms AlCl _{3 and the} like. This corrosion progresses indefinitely in a cyclical manner, and the wiring layer is damaged.

Therefore, in order to form a wiring layer in which corrosion does not occur, for example, after the wiring layer having a photoresist is dry-etched with a gas containing chlorine gas, nitrogen (N ₂ ) is supplied into the post-processing chamber reaching 250 ° C. Then, a method of performing ashing by adding a fluorine-based gas together with H ₂ O vapor and O ₂ and N ₂ gas radicalized by microwaves is disclosed (for example, see Patent Document 1).

However, this disclosed method allows the reaction product to be removed roughly, but is not necessarily sufficient to suppress the corrosion for a longer time, and the photoresist is in an atmosphere reaching 250 ° C. In order to remove the photoresist, the photoresist is usually not cured sufficiently in the subsequent ashing process because the photoresist is cured and placed in an atmosphere that exceeds the curing temperature of the photoresist from the beginning. Has the problem that ashing for a long time is required.
JP 2005-166887 A

  An object of the present invention is to provide a method of manufacturing a semiconductor device that suppresses generation of a reaction product residue and a photoresist residue.

  According to a method for manufacturing a semiconductor device of one embodiment of the present invention, a process of dry etching a wiring layer formed over a semiconductor substrate using a chlorine-based gas using a photoresist as a mask, and the photoresist and the pattern are formed. The wiring layer and the semiconductor substrate having the reaction product are set to a first temperature lower than the sublimation temperature of the reaction product and the curing temperature of the photoresist, and have at least one of H radical and OH radical. The semiconductor substrate is exposed to the first plasma, and then the temperature of the semiconductor substrate is raised while maintaining the first plasma atmosphere, and the second temperature at which the ashing rate of the photoresist due to O radicals rapidly increases is reached. In addition, the second plasma having at least the O radical is switched to, and then the second plasma atmosphere is not maintained. Et al., Raised to a temperature not exceeding 250 ° C., characterized in that it comprises the step of performing the reaction product removal and the photoresist removed.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the manufacturing method of the semiconductor device which suppresses generation | occurrence | production of the reaction product residue and the photoresist residue.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same components are denoted by the same reference numerals.

  A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view of a dry etching apparatus used for manufacturing a semiconductor device. FIG. 2 is a cross-sectional view schematically showing a method for manufacturing a semiconductor device in the order of steps. FIG. 3 is a diagram schematically showing a temperature sequence used for manufacturing a semiconductor device. FIG. 4 is a diagram schematically showing a relative value of the ashing rate with respect to the processing temperature.

  As shown in FIG. 1, the dry etching apparatus 1 employs a multi-chamber method, and an etching chamber 11 for dry etching, a post-processing chamber 13 for ashing, and a cooling chamber 15 for cooling a semiconductor substrate are vacuum-conveyed. The chamber 17 and the semiconductor substrate (not shown) are arranged around the gate valve so that they can be taken in and out. A load lock chamber 18 for taking a semiconductor substrate into and out of the dry etching apparatus 1 is connected to the vacuum transfer chamber 17 via a gate valve. In the center of the vacuum transfer chamber 17, a transfer robot 19 for loading and unloading the semiconductor substrate into and from the chambers 11, 13, 15 and 18 is disposed. In FIG. 1, the etching chamber 11 and the post-processing chamber 13 are arranged one by one in the dry etching apparatus 1, but one or more processing chambers responsible for time-consuming processes can be arranged. It is.

  Although not shown, the dry etching apparatus 1 is connected to the chambers 11, 13, 15, 17, and 18 with necessary gas lines, vacuum pumps, etc., and requires the necessary gas. It is possible to supply a certain amount and maintain a desired degree of vacuum while supplying gas. The support table on which the semiconductor substrate in the etching chamber 11 and the post-processing chamber 13 is placed is configured to be heated to a desired temperature.

The etching chamber 11 has a configuration capable of generating high-density plasma by, for example, a well-known ICP (Inductively Coupled Plasma) method, applying a bias, and drawing the generated plasma onto a semiconductor substrate. The post-processing chamber 13 has a configuration capable of introducing a microwave (for example, 2.45 GHz) into a plasma and converting the gas that has flowed into the semiconductor substrate. The cooling chamber 15 is supplied with nitrogen (N ₂ ), and a dummy semiconductor substrate at almost room temperature is disposed. In addition, if the support stand of the post-processing chamber 13 has a cooling mechanism using a cooling element or cooling water, the cooling chamber 15 is not necessarily required.

  Next, a method for manufacturing a semiconductor device will be described. As shown in FIG. 2A, an insulating film 23 such as a TEOS (Tetra-Ethoxysilane) film is formed on a semiconductor substrate 21 in which an element region (not shown) is formed, and a barrier metal layer is formed on the insulating film 23. A photoresist layer patterned by a well-known lithography process on which a wiring layer 25 having a thickness of about 0.6 μm composed of an AlSiCu layer containing Al as a main component and an antireflection film is formed. The film 27 is formed with a thickness of about 1.5 μm. The semiconductor substrate 21 having the photoresist film 27 is accommodated in, for example, a cassette (not shown), is carried into the load lock chamber 18, is brought into a vacuum state, and is carried by the carrying robot 19 in the vacuum carrying chamber 17. It is placed on the support base of the etching chamber 11.

As shown in FIG. 2B, a chlorine-based gas, for example, Cl ₂ / BCl _2, is introduced into the etching chamber 11, dry etching is performed with high-density Cl ₂ / BCl ₂ plasma, and an exposed wiring layer is formed. 25 is etched away, and the reaction product 31 adheres to the side wall and the like. In the reaction product 31, chlorine, a chlorine-based product derived from the wiring layer 25 and the photoresist film 27 remain. Note that the upper surface of the insulating film 23 may be slightly etched by dry etching using Cl ₂ / BCl ₂ plasma.

  The dry-etched semiconductor substrate 21 is unloaded from the etching chamber 11 by the transfer robot 19 in the vacuum transfer chamber 17 and placed on a support table (not shown) at about 100 ° C. in the post-processing chamber 13. In addition, when performing an ashing process continuously, the support stand of the post-processing chamber 13 is heated to about 250 degreeC. Therefore, by bringing a dummy semiconductor substrate at approximately room temperature in the cooling chamber 15 into contact, the support base can be cooled to 100 ° C. or lower and maintained at about 100 ° C. when the semiconductor substrate 21 is introduced.

Here, the temperature sequence in the post-processing chamber 13 will be described. As shown in FIG. 3, the semiconductor substrate 21 in the post-processing chamber 13 is a first plasma having H radicals, OH radicals, O radicals, etc. introduced by introducing water vapor (H ₂ O) at about 100 ° C. Exposure to an atmosphere of water vapor plasma for 10 seconds. After 10 seconds, the semiconductor substrate 21 is heated at a temperature rising rate of about 2 ° C./second in an atmosphere of water vapor plasma. After 45 seconds, the water vapor is stopped at about 170 ° C., and oxygen is used instead. Then, in an atmosphere of oxygen plasma, which is the second plasma having O radicals, it is heated to about 250 ° C. after 85 seconds and maintained at about 250 ° C. for 20 seconds. After 105 seconds, oxygen is stopped, heating of the support base is stopped, and nitrogen or the like is introduced instead, and the semiconductor substrate 21 is cooled.

  The processing conditions in the post-processing chamber 13 when the temperature of the semiconductor substrate 21 is about 100 to 170 ° C. are, for example, water vapor 500 cc / min, pressure 270 Pa, microwave power 800 W, and the temperature of the semiconductor substrate 21 is about 170 to 250 ° C. The processing conditions in are, for example, oxygen 4000 cc / min and nitrogen 500 cc / min, pressure 270 Pa, and microwave power 1400 W.

  As shown in FIG. 2C, the removal of the reaction product 31 is proceeding at about 170 ° C. when the atmospheric gas is switched from water vapor to oxygen. The removal of the photoresist 27 is performed by removing the reaction product 31. Compared to, progress is slow. Thereafter, by further raising the temperature in oxygen plasma, the removal of the photoresist 27 proceeds rapidly, and at the same time, the removal of the reaction product 31 derived from the photoresist 27 proceeds.

  As shown in FIG. 4, the rate at which the photoresist 27 is removed (ashing rate) in an oxygen plasma atmosphere having O radicals shows a relatively gradual increase up to around 170 ° C. and exceeds 170 ° C. A rapid increase is shown at 210 ° C. to 250 ° C. with a high value. It is known that when the temperature exceeds 250 ° C. and above 270 ° C., carbonization of the photoresist 27 proceeds rapidly and the ashing rate decreases. The temperature of about 170 ° C. is a temperature in the vicinity where the removal rate of the photoresist 27 suddenly increases.

  As shown in FIG. 2D, when the processing at about 250 ° C. is completed in oxygen plasma after 105 seconds, the temperature of the semiconductor substrate 21 is lowered. Then, the reaction product 31 and the photoresist 27 attached to the sidewalls of the wiring layer 25 are substantially completely removed. As a result, the wiring layer 25 to which the pattern of the photoresist 27 is transferred is obtained.

  As described above, the processing of the semiconductor substrate 21 in the post-processing chamber 13 is started at about 100 ° C., which is lower than the sublimation temperature of 144 ° C. of chloride forming a part of the reaction product 31 and lower than the curing temperature of the photoresist 27. The In the post-treatment chamber 13, water vapor is introduced to form an atmosphere of water vapor plasma having H radicals, OH radicals, O radicals, and the like.

The water vapor plasma has a high reactivity with the reaction product 31 containing a chlorine-based gas, and the removal effect increases as the temperature rises from about 100 ° C. AlCl ₃ , Al ₂ Cl _6, etc. constituting the reaction product 31 react with H radicals of water vapor plasma to produce Al and HCl, for example, while reacting with OH radicals of water vapor plasma to produce Al ( OH) ₃ and HCl are produced. The generated HCl is removed from the post-processing chamber 13 by evacuation without returning almost to the wiring layer 25. When the temperature exceeds 144 ° C., the chloride forming a part of the reaction product 31 starts sublimation, and the removal effect is further increased.

  Since the temperature of about 100 ° C. is relatively low, the removal of the photoresist 27 starts although the removal speed is slow. Thereafter, at a temperature rise to about 170 ° C., the water vapor plasma reacts with the photoresist 27 before curing or with the photoresist 27 whose surface or the like has been altered, and the removal of the photoresist 27 is accelerated.

  After 45 seconds from the start of processing in the post-processing chamber 13, when the semiconductor substrate 21 reaches about 170 ° C., it is switched to oxygen plasma. When the temperature exceeds about 170 ° C., the removal rate of the photoresist 27 is further increased to about 250 ° C. The oxygen plasma having a high removal rate of the photoresist 27 reacts and proceeds to be removed before the curing progresses and the reaction with the photoresist 27 hardly occurs. Meanwhile, during this time, the reaction product 31 is vaporized by sublimation, oxidation reaction, and the like, and is removed from the post-processing chamber 13 by vacuuming. As a result, the photoresist 27 on the wiring layer 25 and the reaction product 31 and the like that cause the corrosion around the wiring layer 25 and the upper surface of the insulating film 23 are substantially all removed.

  Setting the processing start temperature of the post-processing chamber 13 to about 100 ° C. is to remove the surface alteration layer of the reaction product 31 before the reaction product 31 starts sublimation, thereby making the subsequent sublimation more efficient. The inventors have found that there is an effect to implement uniformly. In particular, it is preferable that the processing start temperature of the post-processing chamber 13 is about 100 ° C. so as not to leave the removal of the reaction product 31 over the entire surface of the large-diameter semiconductor substrate 21.

  Note that setting the processing start temperature in the post-processing chamber 13 to a temperature lower than about 100 ° C. is not efficient because it takes a longer time to raise the temperature, and the processing time is longer. For example, when the processing start temperature is room temperature, the water vapor plasma has an effect of removing the photoresist 27 and the reaction product 31 from room temperature to about 100 ° C., but the reaction rate is low, and Processing time is hardly reduced. Further, when the semiconductor substrate 21 is continuously processed, for example, after the processing, it is necessary to lower the temperature from about 250 ° C. to room temperature, and extra time is required as compared with the temperature lowering to about 100 ° C.

  When the temperature exceeds 250 ° C. and reaches about 270 ° C. or more, carbonization of the photoresist 27 proceeds rapidly, and ashing hardly occurs. If the temperature does not exceed 250 ° C., Al alteration or the like hardly occurs. Therefore, it is preferable to perform ashing in oxygen plasma up to 250 ° C.

  When the semiconductor substrate 21 having the wiring layer 25 formed by the manufacturing method of the semiconductor device was observed with a microscope, the remainder of the photoresist 27 could not be found on the upper surface of the wiring layer 25. Further, the semiconductor substrate 21 was left in the atmosphere for 48 hours, and the side surface and the upper surface of the wiring layer 25 were observed. However, the occurrence of corrosion could not be found. As a result, in the semiconductor substrate 21 having the wiring layer 25 of this embodiment, the reaction product 31 that causes corrosion is substantially all removed, and at the same time, the photoresist 27 is substantially removed from the upper surface of the wiring layer 25 and the like. All have been removed.

  As a result, a semiconductor device such as an LSI formed by the above-described method for manufacturing a semiconductor device has a high yield and is stable and becomes a highly reliable product.

  Further, the dry etching apparatus adopts a multi-chamber method, and the etching chamber 11 for dry etching and the post-processing chamber 13 for ashing are arranged separately and can perform each processing independently of each other. Is possible. Accordingly, the processing can be efficiently performed without necessarily being limited to one processing time. Further, by disposing the cooling chamber 15 and holding the dummy semiconductor substrate at room temperature, it becomes possible to easily cool the support base of the post-processing chamber 13 and improve the processing speed of the semiconductor substrate 21. Is possible.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, It can implement in various deformation | transformation within the range which does not deviate from the summary of this invention.

  For example, in the embodiments, a method of first introducing water vapor and then oxygen as gas species to form plasma and removing the photoresist 27 and the reaction product 31 has been described. However, it is necessary to limit to these gas species. However, the same effect can be obtained by adding other gas species mainly containing water vapor and oxygen. For example, at about 100 to 170 ° C., water vapor can be the main component and oxygen can be the subcomponent. Further, at 170 to 250 ° C., it is possible to use oxygen as a main component and water vapor as a subcomponent. Further, at 170 to 250 ° C., it is possible to use oxygen as a main component and nitrogen and water vapor as subcomponents. Moreover, it is possible to add a fluorine-type gas as a subcomponent in each case mentioned above at 170-250 degreeC.

  In the embodiment, the method for removing the photoresist 27 and the reaction product 31 by introducing water vapor to generate H radical, OH radical, and O radical has been described. However, the H radical, OH radical, and Other materials can be used as long as O radicals can be generated.

The present invention can be configured as described in the following supplementary notes.
(Supplementary Note 1) A step of dry etching a wiring layer formed on a semiconductor substrate using a chlorine-based gas with a photoresist as a mask, the photoresist, the patterned wiring layer, and a reaction product Exposing the semiconductor substrate to a first plasma having at least one of H radicals and OH radicals at a first temperature lower than a sublimation temperature of the reaction product and a curing temperature of the photoresist; While maintaining the first plasma atmosphere, the temperature of the semiconductor substrate is raised, and the second temperature at which the ashing rate of the photoresist by O radicals rapidly increases becomes a boundary. Then, while maintaining the second plasma atmosphere, the temperature does not exceed 250 ° C. And a step of removing the reaction product and removing the photoresist.

(Supplementary Note 2) The step of performing the dry etching and the step of removing the reaction product and removing the photoresist are performed in separate processing chambers, and the transfer of the semiconductor substrate between the processing chambers maintains a vacuum. The manufacturing method of the semiconductor device according to attachment 1, which is performed in a state.

(Supplementary note 3) The semiconductor device manufacturing method according to supplementary note 1, wherein the semiconductor substrate is cooled in a cooling chamber into which nitrogen gas is introduced.

The typical top view of the dry etching apparatus used for manufacture of the semiconductor device concerning the example of the present invention. Sectional drawing which shows typically the manufacturing method of the semiconductor device which concerns on the Example of this invention in order of a process. The figure which shows typically the temperature sequence used for manufacture of the semiconductor device which concerns on the Example of this invention. The figure which shows typically the relative value of the ashing rate with respect to the process temperature which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dry etching apparatus 11 Etching chamber 13 Post-processing chamber 15 Cooling chamber 17 Vacuum transfer chamber 18 Load lock chamber 19 Transfer robot 21 Semiconductor substrate 23 Insulating film 25 Wiring layer 27 Photoresist 31 Reaction product

Claims (5)

A step of dry etching the wiring layer formed on the semiconductor substrate using a chlorine-based gas with a photoresist as a mask;
The semiconductor substrate having the photoresist, the patterned wiring layer, and the reaction product is set to a first temperature lower than a sublimation temperature of the reaction product and a curing temperature of the photoresist, and H Exposure to a first plasma having at least one of radicals and OH radicals, and then the temperature of the semiconductor substrate is raised while maintaining the first plasma atmosphere, and the ashing rate of the photoresist due to O radicals is rapidly increased. Switching to the second plasma having at least the O radical at the boundary of the second temperature becoming higher, and then increasing the temperature to not exceed 250 ° C. while maintaining the second plasma atmosphere, Performing reaction product removal and photoresist removal;
A method for manufacturing a semiconductor device, comprising:   The method of manufacturing a semiconductor device according to claim 1, wherein the first plasma is formed from water vapor.   The method of manufacturing a semiconductor device according to claim 1, wherein the second plasma is formed from oxygen.   4. The method of manufacturing a semiconductor device according to claim 1, wherein the first temperature is about 100 ° C. 5.   5. The method of manufacturing a semiconductor device according to claim 1, wherein the second temperature is about 170 ° C. 6.

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