1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method, and more particularly to a substrate processing apparatus and a substrate processing method which are useful for carrying out wet processing of a surface of the substrate by bringing the surface of the substrate into contact with a processing liquid, such as a liquid chemical or pure water.
2. Description of the Related Art
In place of dry processes which have been principally employed for the formation of LSI interconnects or the like on a semiconductor substrate, wet processes, such as plating, chemical-mechanical polishing (CMP), electrolytic etching, electrolytic polishing and cleaning, are increasing being employed these days. For example, a so-called damascene process, which comprises embedding a metal (conductive material), such as aluminum, and more recently silver or copper, by plating into interconnect trenches and contact holes formed in the surface of a substrate, followed by removal of an extra metal by CMP, is becoming to be used.
Next, as shown in
It is common practice in dry processes to control the static electricity of a substrate. In contrast, no great importance has hitherto been attached to the control of the static electricity of a substrate in wet processes.
A substrate in a dry state, which has been taken out of the substrate cassette 10 and placed on the stage 14 by the first substrate transport robot 22, is transported by the second substrate transport robot 24 to the electroplating apparatus 20 where electroplating of the substrate is carried out. The substrate after plating is transported to the post-cleaning apparatus 16 where the substrate is post-cleaned and dried. Thereafter, the substrate is placed on the stage 14, and is then returned by the first substrate transport robot 22 to the original position in the substrate cassette 10.
When a substrate in a dry state, which has been carried into an apparatus frame, is in a charged state, particles, organic or inorganic compounds, etc., having the opposite polarity, are likely to be adsorbed to the surface of the substrate. Further, in case a liquid chemical (processing liquid), such as a plating solution, for wet processing has a polarity, the contact efficiency between the processing liquid and the substrate can decrease, which can result in defective processing in a local or global region of the substrate.
This defective processing becomes more marked as the processing size of substrate decreases. For example, a decrease in yield due to defective processing becomes a considerable problem when forming 90 nm-node or later-generation interconnects by the above-described damascene process, though it is negligible with 130 nm-node interconnects. Further, the type of interconnect material affects defective processing. In particular, though there is almost no appreciable defective processing with aluminum interconnects, defective processing is marked with copper interconnects. In addition, use of a low-k material, such as an organic material or a porous material, for an insulating film increases defective processing.
The defective processing herein refers to deficient metal deposition, uneven metal deposition, etc. in plating, insufficient polishing, over-polishing, pit formation, corrosion, etc. in CMP or electrolytic processing, and poor cleaning, corrosion, etc. in cleaning.
The present invention has been made in view of the above situation in the related art. It is therefore an object of the present invention to provide a substrate processing apparatus and a substrate processing method which can appropriately control the charge of a substrate depending on the type of wet processing, thereby reducing defective processing due to static electricity on a surface of the substrate.
In order to achieve the above object, the present invention provides a substrate processing apparatus comprising: a static electricity adjustment section for adjusting static electricity on a substrate; and a wet processing apparatus for carrying out wet processing of the static electricity-adjusted substrate.
The wet processing apparatus may be comprised of at least one of an electroplating apparatus, an electroless plating apparatus, a CMP apparatus, an electrolytic etching apparatus, an electrolytic polishing apparatus, a chemical etching apparatus and a cleaning apparatus.
The static electricity adjustment section may be adapted to remove static electricity from the substrate. The removal of static electricity can be effected, for example, by grounding the substrate.
Alternatively, the static electricity adjustment section may be adapted to charge the substrate into a desired charged state. In this case, the static electricity adjustment section may include a static electricity sensor for detecting the charge of the substrate, a charging unit for charging the substrate, and a control section for controlling the charging unit.
The static electricity adjustment section may be provided in at least one of a substrate transport robot for transporting the substrate to the wet processing apparatus, a substrate transport route for transport of the substrate to the wet processing apparatus, and the wet processing apparatus.
According to the substrate processing apparatus of the present invention, the static electricity adjustment section can appropriately control the charge of a substrate, depending on the type of wet processing, for example, by removing static electricity (electric charge) from the substrate or charging the substrate into a desired charged state, so that wet processing can be carried out on the substrate in the appropriately controlled charged state. This can reduce defective processing, thereby increasing the yield of the device.
The present invention also provides a substrate processing method comprising: adjusting static electricity on a substrate; and carrying out wet processing of the static electricity-adjusted substrate.
According to the present invention, static electricity on a surface of the substrate is arbitrarily adjusted prior to carrying out wet processing of the surface of the substrate. This makes it possible to produce an LSI or the like in a high yield even in a future generation when finer interconnects of more advanced material are employed. The present invention can thus contribute to cost reduction of electronic products.
Preferred embodiments of the present invention will now be described with reference to the drawings.
The substrate processing apparatus of this embodiment is also provided with a static electricity adjustment section 30, located in an area surrounded by the first substrate transport robot 22, the stage 14 and one of the post-cleaning apparatuses 16, for detecting the charge of the substrate on the stage 14 and charging the substrate into a charged state suited for wet processing (electroplating).
As shown in detail in
The static electricity sensor 32 and the charging blower 38 may be exemplified by “SK Series” and “SJ-F100/010”, respectively, both manufactured by Keyence Corporation.
According to this embodiment, one substrate W, in a dry state, is taken by the first substrate transport robot 22 out of the substrate cassette 10, and the substrate W is carried into the apparatus frame 12 and placed on the stage 14. The charge of the substrate W on the stage 14 is detected with the static electricity sensor 32. Based on the charge detected, the static electricity adjustment section 30 charges the substrate W on the stage 14 into a desired positively or negatively charged state suited for electroplating using a plating solution (processing liquid) having a large polarity.
Next, the substrate in the thus-adjusted charged state is transported by the second substrate transport robot 24 to the electroplating apparatus 20. In the electroplating apparatus 20, for example, copper is filled into contact holes 3 and interconnect trenches 4, and a copper film 6 is deposited on an insulating film 2, as shown in
The substrate W after plating is transported to the post-cleaning apparatus 16 for post-cleaning and drying of the substrate W. The dried substrate W is placed on the stage 14, and is then returned by the first substrate transport robot 22 to the original position in the substrate cassette 10.
According to this embodiment, the static electricity adjustment section for removing static electricity (electric charge) from the substrate W is comprised of a conductive wire 50 which is grounded at one end and at the other end is connected to the substrate W held by the substrate holder 44. Thus, according to this embodiment, the substrate W, when held by the substrate holder 44, is grounded via the conductive wire (static electricity adjustment section) 50, whereby static electricity is removed from the substrate W. Accordingly, electroplating of the substrate can be carried out always in the electricity-removed state.
It is, of course, possible to provide this static electricity adjustment section in the second substrate transport robot 24. Further, it is possible to use a combination of the static electricity adjustment sections shown in
According to this embodiment, one substrate W, in a dry state, is taken by the first substrate transport robot 22 out of the substrate cassette 10, and the substrate W is carried into the apparatus frame 12 and placed on the stage 14. The charge of the substrate W on the stage 14 is detected with the static electricity sensor 32. Based on the charge detected, the static electricity adjustment section 30 charges the substrate W on the stage 14 into a desired positively or negatively charged state suited for, for example, pretreatment using a pretreatment liquid (processing liquid) or electroless plating using an electroless plating solution (processing liquid).
It is also possible, for example, to charge the substrate by the static electricity adjustment section 30 into a desired positively or negatively charged state suited for pretreatment using a pretreatment liquid (processing liquid), and remove static electricity from the substrate in the electroless plating apparatus 76 by the static electricity adjustment section comprising the conductive wire 50, shown in
Next, the charge-adjusted substrate is transported by the second substrate transport robot 24 to the pre-cleaning apparatus 70 where the surface of the substrate is pre-cleaned, and the substrate is then transported to the pretreatment apparatus 72 where pretreatment of the surface of the substrate is carried out. Thereafter, the substrate is transported to the electroless plating apparatus 76 where a plated film is formed on the pre-treated surface of the substrate. Thereafter, the substrate is transported to the post-cleaning apparatus 78 where the surface of the substrate is post-cleaned, and the substrate is then transported to the drying apparatus 80 where the substrate is dried. The dried substrate is placed on the stage 14, and is then returned by the first substrate transport robot 22 to the original position in the substrate cassette 10.
Electroless plating involves various wet processings using processing liquids having a large polarity, such as a pretreatment liquid and an electroless plating solution. Therefore, control of the static electricity of a substrate is of especial importance.
According to this embodiment, one substrate W, in a dry state, is taken by the first substrate transport robot 22 out of the substrate cassette 10, and the substrate W is carried into the apparatus frame 12 and placed on the stage 14. The charge of the substrate W on the stage 14 is detected with the static electricity sensor 32. Based on the charge detected, the charging blower 38 charges the substrate W on the stage 14 into a desired positively or negatively charged state suited for reducing a local cell effect as produced upon polishing materials of different electric potentials, for example, the copper film 6, the barrier layer 5 and the insulating film 2 shown in
Next, the charge-adjusted substrate is transported to the CMP apparatus 88. In the CMP apparatus 88, for example, the copper film 6, the seed layer 7 and the barrier layer 5 on the insulating film 2 are removed into a flat surface, as shown in
The substrate after polishing is transported to the chemical cleaning apparatus 84 where the surface of the substrate is cleaned with a liquid chemical (processing liquid), and the substrate is then transported to the pure water-cleaning apparatus 82 where the substrate is cleaned with pure water. Thereafter, the substrate is transported to the drying apparatus 90 where the substrate is dried. The dried substrate is placed on the stage 14, and is then returned by the first substrate transport robot 22 to the original position in the substrate cassette 10.
According to this embodiment, one substrate W, in a dry state, is taken by the first substrate transport robot 22 out of the substrate cassette 10, and the substrate W is carried into the apparatus frame 12 and placed on the stage 14. The charge of the substrate W on the stage 14 is detected with the static electricity sensor 32. Based on the charge detected, the charging blower 38 charges the substrate W on the stage 14 into a desired positively or negatively charged state suited for reducing the local cell effect, inhibiting adhesion of particles to the substrate and promoting removal of residual matter from the substrate.
Next, the charge-adjusted substrate is transported to the cleaning apparatus 98, where the surface of the substrate is cleaned with a cleaning liquid (liquid chemical). Since the substrate W is in the charged state suited for cleaning, defective processing due to static electricity, such as poor cleaning, corrosion, etc., can be suppressed even in a generation when finer interconnects of more advanced interconnect material are employed.
The substrate after cleaning is transported to the back surface-cleaning apparatus 94 where the back surface of the substrate is cleaned, and the substrate is then transported to the drying apparatus 92 where the substrate is dried. Thereafter, the dried substrate is placed on the stage 14, and then returned by the first substrate transport robot 22 to the original position in the substrate cassette 10.
Though the above embodiments use an electroplating apparatus, an electroless plating apparatus, a CMP apparatus and a cleaning apparatus as wet processing apparatuses, it is of course possible to use other wet processing apparatuses, such as an electrolytic etching apparatus, an electrolytic polishing apparatus and a chemical etching apparatus.
A description will now be given of an experiment that was conducted to examine the relationship between charge on a substrate and defective processing. In particular, copper electroplating and CMP after the plating of a substrate were carried out in the following cases: without a static electricity treatment of the substrate; after removing static electricity from the substrate; after charging the substrate with a positive charge of +1 kV; and after charging the substrate with a negative charge of −1 kV. In each case, the amount of static electricity on the substrate, the number of defects in copper plating and corrosion upon CMP were measured on the substrate. The results are shown in Table 1.
As will be appreciated from Table 1, the optimum charge value for electroplating does not necessarily coincide with that for CMP. A suitable charge for a substrate may thus differ depending on the type of processing of the substrate. This is considered to be due to different electrolytes or polar compounds employed. Though the mechanism in this regard is not fully elucidated yet and is subject of future investigation, it is clear that control of the static electricity of a substrate can minimize defective processing and can therefore increase the device yield.
Number | Date | Country | Kind |
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2004-128778 | Apr 2004 | JP | national |