JP2645420B2 - Ashing equipment - Google Patents

Description

The present invention relates to an ashing device.

(Prior Art) In general, a fine pattern of a semiconductor integrated circuit is formed by etching and diffusing a base film formed on a semiconductor wafer using a photoresist film of an organic polymer patterned by exposure and phenomenon as a mask. , By implanting impurities.

Therefore, the photoresist film used as a mask needs to be removed from the surface of the semiconductor wafer after the etching process. An ashing process is performed as an example of a process for removing the photoresist film in such a case. This process is practical in that an unnecessary resist film can be selectively removed without damaging the exposed base film. The ashing process is also used for removing resist, cleaning silicon wafers and masks, removing ink, removing solvent residues, and the like, and is suitable for performing a dry cleaning process in a semiconductor process.

As an ashing apparatus for removing a photoresist film, an apparatus using an ozone-containing gas is disclosed, for example, in Japanese Patent Application Laid-Open No. 52-20766. In this method, a plurality of ashing gas inflow holes are provided above, and a semiconductor wafer which can be sequentially conveyed by belt conveyance is set below the plurality of ashing gas inflow holes. Is supplied to perform an ashing process, thereby performing uniform ashing.

In order to further increase the ashing speed, a technique is also used in which an ashing gas heated in advance is supplied into a processing chamber, and the ashing gas flows out to a surface of a semiconductor wafer set in the processing chamber to perform an ashing process.

(Problems to be Solved by the Invention) However, in the technique disclosed in Japanese Patent Application Laid-Open No. 52-20766, ashing is performed uniformly by flowing an ashing gas into the surface of a semiconductor wafer while the semiconductor wafer is sequentially transported. However, this is only to heat the semiconductor wafer from the lower surface to a predetermined temperature in order to obtain a desired ashing uniformity and ashing speed. When the semiconductor wafer is supplied to the surface, the semiconductor wafer is cooled due to the contact and flow with the ashing gas, so that the desired ashing uniformity and ashing speed cannot be obtained. It is extremely difficult to precisely set the temperature of the semiconductor wafer to the desired temperature by heating only the lower surface of the semiconductor wafer.

Further, in the technique of supplying the preheated ashing gas into the processing chamber and flowing the ashing gas into the surface of the semiconductor wafer set in the processing chamber, the ashing gas, for example, the ozone gas is heated and activated, and the activated ashing gas is activated. The time and distance required for the ozone gas to reach the semiconductor wafer surface is long, so that the activated ozone gas becomes inactive, that is, becomes oxygen molecules or the like by bonding with other molecules, making the ashing process difficult. . That is, since the lifetime of oxygen atom radicals generated by heating the ozone gas is very short, the time and distance from when the ashing gas is heated to when it reaches the semiconductor wafer surface are affected. Therefore, there is a problem that the amount of ozone that contributes to the ashing process of the semiconductor wafer is reduced, and as a result, the ashing speed is reduced.

The present invention has been made in view of such a point,
It is an object of the present invention to provide an ashing apparatus which can perform an ashing process which is more uniform and faster than before.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a substrate to be processed is located at a position opposed to an inflow hole through which an ashing gas flows into a processing chamber, and ashing gas is supplied from the inflow hole. In the apparatus for ashing a substrate to be processed by flowing and contacting the surface of the substrate to be processed, the inflow hole and an exhaust hole for exhausting the ashing gas flowing from the inflow hole out of the processing chamber are provided in an upper portion of the processing chamber. A plurality of gas inflow / outflow portions are formed on the same surface, and a transport portion that moves the substrate to be processed in parallel with the gas inflow / outflow portion at a predetermined interval is provided at a lower portion in the processing chamber. The inflow holes and the outflow holes are formed in a slit shape, and the inflow holes and the outflow holes are arranged alternately and in parallel with each other. The holes are arranged so as to be perpendicular to the direction of movement of the substrate to be processed by the transfer unit.

(Operation) According to the ashing device of the present invention, the inflow hole and the discharge hole are formed on the same surface in the inflow and discharge portion provided in the upper portion of the processing chamber, and the inflow hole and each of the discharge holes are each slit. In addition to being formed into a shape, they are arranged alternately and in parallel with each other, and furthermore, since these inflow holes and discharge holes are arranged so as to be perpendicular to the moving direction of the substrate to be processed, With the movement of the substrate, the slit-like inflow hole and discharge hole are scanned alternately on the surface of the substrate to be processed, and uniform contact and discharge of the ashing gas are performed. In addition, when viewed from a macro perspective, the gas flow from the inflow hole to the discharge hole becomes a bulk flow and is parallel to the moving direction of the substrate to be processed. Accordingly, uniform and high-speed ashing processing can be performed on the substrate to be processed.

(Embodiment) An embodiment in which the present invention is applied to a semiconductor wafer ashing processing apparatus will be described below with reference to the drawings.

In this embodiment, the relative movement between the substrate to be processed and the gas inflow / emission unit will be described with reference to an embodiment in which the substrate to be processed, that is, the semiconductor wafer is moved. In the processing chamber 11, there is disposed a transfer section 13 which is constituted by a transfer belt 13a of, for example, a metal wire, and which is formed by a belt conveyor on which a substrate to be processed, for example, a semiconductor wafer 12, is loaded and transferred. A heating unit 15 for heating the semiconductor wafer 12 is disposed below the semiconductor wafer 12, and the heating unit 15 has a built-in heater 15a controlled by a temperature control device 14.

As shown in FIGS. 2 and 3, an ashing gas inflow hole and a discharge hole having a width of, for example, about 0.1 to 5 mm and formed of a plurality of parallel elongated slit-like grooves are provided above the transport section 13. Gas inlet / outlet part 17 composed of certain openings 17a to 17j
For example, glass plates are arranged to face each other, and the gas inflow / outflow portion 17 is cooled by cooling water or the like circulated from the cooling device 16.

The openings 17a to 17e, which are the inflow holes of the ashing gas, of the gas inflow / emission unit 17 are connected to a gas flow controller 18, and the gas flow controller 18 is connected to an ozone generator 20 connected to an oxygen supply source 19. It is connected to the.

On the other hand, openings 17f to 17j, which are discharge holes of the ashing gas of the gas inflow / outflow portion 17, are connected to the exhaust device 21.

Further, the gas inflow / outflow portion 17 incorporates a heating means, for example, a heater 22, which is embedded so as to surround the openings 17a to 17j. The temperature of the heater 22 is controlled by a temperature controller 23, and the heater 22 is configured to heat the gas inflow / outflow unit 17 to heat the ashing gas passing through the openings 17a to 17j and to heat the surface of the semiconductor wafer 12. I have.

Further, the openings 17a to 17e of the gas inflow / emission unit 17 are connected to a gas flow controller 25 connected to another second gas supply source 24 in addition to the gas flow controller 18, and It is configured to be able to flow in accordingly.

An input chamber 26 for storing the unprocessed semiconductor wafer 12 is provided on the right outside the processing chamber 11, and an unloading chamber 27 for storing the processed semiconductor wafer 12 is provided on the left outside the processing chamber 11. ing. The semiconductor wafer 12 is carried, for example, in a direction perpendicular to the grooves of the openings 17a to 17j of the gas inflow / emission unit 17. In this ashing apparatus having the above configuration, the ashing process is performed as follows.

First, the semiconductor wafers 12 accommodated in the loading chamber 26 are sequentially loaded into the processing chamber 11 by a loading device (not shown), and then a plurality of semiconductor wafers 12 are sequentially placed on the transport belt 13a of the transport unit 13, and a drive (not shown) The transport belt 13a is moved leftward at the same speed as the transport belt 13a moved by the apparatus, for example, at a speed of about 1 to 50 mm / sec.

Then, the heater 15a is controlled by the temperature controller 14 to heat the semiconductor wafer 12 to, for example, about 100 to 350 ° C., and the oxygen gas containing ozone supplied from the oxygen supply source 19 and the ozone generator 20 is supplied at a gas flow rate. The controller 18 allows the flow rate per semiconductor wafer to be, for example, 7.5 to 20 sl /
min (sl is the flow rate at normal temperature and normal pressure), and the gas flows from the gas inflow / outflow section 17 toward the semiconductor wafer 12. The gas pressure in the processing chamber 11 is reduced by the exhaust device 21, for example.
Evacuate so as to be in the range of about 200 to 700 Torr.

At the same time, the temperature of the heater 22 incorporated in the gas inflow / outflow section 17 is controlled by the temperature control device 23 to heat the gas inflow / outflow section 17 to, for example, about 20 to 300 ° C.

At this time, as shown by arrows in FIG.
A flow of gas inflow and outflow is formed between the semiconductor wafer 12 and the semiconductor wafer 12. Then, when viewed macroscopically, this flow forms an overall flow that exits from the openings 17a to 17e and is discharged to the openings 17f to 17j, that is, a bulk flow, and this flow is a flow of the semiconductor wafer 12. Becomes parallel to the transport direction.

Here, the ozone O ₃ contained in the gas is heated to a temperature at which it is not decomposed immediately before inflow by the gas inflow / outflow unit 17 and faces the semiconductor wafer 12, and contacts the surface of the semiconductor wafer 12. It is further decomposed by heating, and a large amount of oxygen atom radicals are generated.

Then, the oxygen atom radicals react with the photoresist film deposited on the surface of the semiconductor wafer 12, and ashing is performed to remove the photoresist film. The waste gas generated by the ashing is immediately exhausted to the outside of the processing chamber 11 by the gas inflow / emission unit 17. At this time, the openings 17f to 17j, which are the ashing gas discharge holes of the gas inflow / emission unit 17, are also heated at the same time, so that mist does not adhere and the contamination of the semiconductor wafer 12 due to the influence of the mist is prevented. be able to. Since such a mist has a characteristic of mainly adhering to a low-temperature portion, the gas inflow / outflow portion 17
Does not adhere to Further, since the gas inflow / emission unit 17 is heated, when exhausting the ashing gas waste gas, ozone remaining in the waste gas can be decomposed at the same time.

Then, the semiconductor wafer 12 which has been transferred to the left side of the processing chamber 11 by the transport belt 13a and has been processed is housed in the unloading chamber 27 by an unshown unloading device.

The life of ozone generated by the ozone generator 20 depends on the temperature. As shown in the graph of FIG. 4, the vertical axis represents the half-life of ozone decomposition and the horizontal axis represents the temperature of the gas containing ozone. The higher the value, the shorter the life of ozone.
For this reason, the temperature of the gas is preferably about 25 ° C. or less, while the temperature of the semiconductor wafer 12 is preferably heated to about 150 ° C. or more.
It is preferred to heat to 50 ° C. or higher.

In the graph of FIG. 5, the vertical axis represents the ashing speed, the horizontal axis represents the flow rate of the gas containing ozone, and the distance gap between the gas inflow / outlet unit 17 and the semiconductor wafer 12 in the ashing apparatus of this embodiment described above is set to 1.5. The graph shows a change in the ashing speed of the semiconductor wafer 12 when the 6-inch semiconductor wafer 12 is heated to 250 ° C. and the gas inflow / outlet unit 17 is heated to 200 ° C. and the moving speed is 10 mm / sec. The ozone concentration is adjusted to be about 3 to 10% by weight. Sixth
The graph in the figure is a characteristic example diagram showing a change in each ashing speed when the gap (interval) between the gas inflow / emission unit 17 and the semiconductor wafer 12 is changed.
It shows that the ashing speed becomes maximum when the distance is about m. Further, the graph of FIG. 7 is a characteristic example diagram showing a change in the ashing speed when the heating temperature of the gas inflow / emission unit 17 is changed.
In this case, the ashing speed is the highest. Since the heating means for the gas inflow / outflow section 17 is provided as described above, the temperature of the gas inflow / outflow section 17 can be varied, and furthermore, the heating temperature of the semiconductor wafer 12 can be independently varied independently. Can be easily set to the processing temperature condition described above and flow into the surface of the semiconductor wafer 12.

In addition, since the ashing speed can be varied by changing the temperature of the gas inflow / emission unit 17, control such as stopping the ashing with a constant remaining film thickness at the end of the ashing process is also possible.

When the semiconductor wafer 12 is moved, the moving direction is set in parallel with the flow of the entire gas flowing in and out of the gas inflow / emission unit 17, that is, the flow of the bulk fluid. After uniformly flowing into the entire surface of the semiconductor wafer 12, the gas is exhausted from above. Therefore, the ashing uniformity is extremely good, for example, as shown in FIG.

In the above embodiment, the movement of the semiconductor wafer 12 is performed by sequentially placing a plurality of semiconductor wafers 12 on the transfer unit 13 and temporarily passing through the reaction space below the gas inflow / outflow unit 17 for a predetermined processing time. However, other movements, for example, the ashing time required at a predetermined speed in the reaction space below the gas inflow / outlet unit 17, a constant stroke, for example, from the opening 17a to the next opening 17b Even if the distance is set to one stroke and the reciprocating motion is performed by the scanning method, the same operation and effect as described above can be obtained. Also, instead of placing and moving the semiconductor wafer on the transport belt, a mounting table is provided, and this mounting table is provided by using a rotary linear mechanism using, for example, an air cylinder, a pulse motor, a servo motor, a stepping motor, or the like. , It may be configured to reciprocate.

Also, in this embodiment, the case of a photoresist film was described as an object to be ashed. However, the object to be ashed can be applied to various things such as solvent removal including ink removal and any object that can be removed by oxidation. The gas containing ozone is not limited to oxygen, and may be a gas which does not react with ozone, particularly an inert gas such as N ₃ , Ar, Ne, etc., which contains ozone.

Further, in the above embodiment, the embodiment applied to the processing of a semiconductor wafer has been described. However, in the case of an ashing process, a photomask provided on a glass substrate, a printed board,
It is needless to say that the present invention can be applied to any of a large display panel and an amorphous silicon film to be deposited.

In particular, delicate materials that are highly susceptible to oxidation, such as ITO film, amorphous silicon (αSi), tantalum (Ta), and chromium (Cr), are used as base films, such as LCD substrates and mask substrates. At the time of ashing, a treatment that does not damage the base film is required.

For example, there is a need for a method in which the ashing is stopped at a certain remaining film thickness and then switched to a wet process. For this purpose, precise ashing control is indispensable. It is very effective.

Further, when performing ashing processing on a large substrate to be processed, the shape of the gas inflow / outflow portion can be increased by adjusting the shape of the gas inflow / outflow portion, that is, by adjusting the length and number of the openings serving as the ashing gas inflow / outflow holes. Scale-up becomes easy.

In addition to the oxygen gas containing ozone as an ashing gas, a second gas such as N ₂ O, NO, N
If ashing is performed by adjusting the flow rate of O ₂ , C ₂ F ₅ , CCl ₄ , CF _4, etc. with the gas flow controller 25 and mixing with the above oxygen gas, the ashing application range is widened and versatile ashing is achieved. It becomes possible.

Further, the ashing rate is constant even if the resist amount or the resist area of each semiconductor wafer is different, and the ashing rate of each semiconductor wafer is the same regardless of the number of semiconductor wafers in the ashing reaction space. That is, since there is no loading effect, the operation is easy.

As described above, according to this embodiment, the heating unit is provided in the gas inflow / outflow unit having the ashing gas inflow hole and the discharge hole provided to face the substrate to be processed,
The ashing gas temperature can be easily set to a temperature at which a desired ashing speed is obtained, and the ashing gas can be heated immediately before the substrate to be processed. Throughput can be improved.

Further, in order to heat the gas inflow / exhaust portion, when exhaust gas of the ashing gas is exhausted from the gas inflow / exhaust portion, no mist adheres to the gas inflow / exhaust portion. It is possible to suppress contamination of the substrate to be processed.

In addition, the substrate to be processed is not only heated from below,
Since the radiant heat of the gas inflow / outflow portion disposed above is also transmitted, it is possible to control the temperature in a desired and constant temperature zone with high reliability.

(Effects of the Invention) According to the ashing apparatus of the present invention, it becomes more like a slit-like inflow hole and an outflow hole are alternately scanned on the surface of the substrate to be processed with the movement of the substrate to be processed. Contact and discharge of the ashing gas are performed. In addition, when viewed from a macro perspective, the gas flow from the inflow hole to the discharge hole becomes a bulk flow and is parallel to the moving direction of the substrate to be processed. Therefore, it is possible to perform an ashing process which is much more uniform and faster than before.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration of an ashing device according to an embodiment of the present invention, FIG. 2 is a bottom view of a gas inflow / outlet portion in the ashing device of FIG. 1, and FIG. FIG. 4 is a graph showing the relationship between the half-life of decomposition of ozone and the temperature in the ashing device of FIG. 1, and FIG.
FIG. 6 is a graph showing the relationship between the ashing speed and the gas flow rate containing ozone in the ashing device shown in FIG. 6, FIG. 6 is a graph showing the relationship between the ashing speed and the gap of the reaction space in the ashing device in FIG. 1, and FIG. FIG. 8 is a graph showing a relationship between an ashing speed and a gas inflow / outlet temperature in the ashing device of FIG. 1, and FIG. 8 is a graph showing a relationship between a remaining resist film thickness and a distance from the center of the semiconductor wafer in the ashing device of FIG. is there. 11 processing chamber, 12 semiconductor wafer 13 transport unit, 15a heater 16 cooling unit, 17 gas inlet / outlet unit 17a-17j opening, 20 ozone generator 22 heater, 23 temperature control unit

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-84029 (JP, A) JP-A-64-42129 (JP, A) Jpn.

Claims (1)

(57) [Claims] A substrate to be processed is located at a position facing an inflow hole through which an ashing gas flows into a processing chamber; and the ashing gas flows from the inflow hole to come into contact with the surface of the substrate to be processed to thereby perform the processing. In an apparatus for ashing a substrate, a gas inflow / outflow portion is formed in the upper portion of the processing chamber, in which a plurality of the inflow holes and a plurality of discharge holes for exhausting the ashing gas flowing through the inflow holes from the processing chamber are formed on the same surface. In a lower portion of the processing chamber, a transfer unit that moves the substrate to be processed in parallel with the gas inflow / outflow unit at a predetermined distance below the gas inflow / outflow unit is provided. While being formed, the inflow holes and the outflow holes are arranged alternately and in parallel with each other. Further, the inflow holes and the outflow holes are directly in the moving direction of the substrate to be processed by the transfer section. An ashing device characterized by being arranged at a corner.