JPH0766917B2 - Ashing method - Google Patents

Description

The present invention relates to an ashing method for removing a photoresist film or the like deposited on a substrate to be processed.

(Prior Art) Generally, a fine pattern of a semiconductor integrated circuit is formed by etching a base film formed on a semiconductor wafer using a photoresist film of an organic polymer formed by exposure and development as a mask. After that, the photoresist film is removed from the surface of the semiconductor wafer. As an example of this removal process, for example, an ashing process is performed.

Examples of the above-mentioned ashing processing device include a device using oxygen plasma, a device using ultraviolet light, and a device using ozone. Among the above, as an ashing device using ozone which has a high ashing speed and does not damage a semiconductor wafer, there is, for example, one disclosed in Japanese Patent Laid-Open No. 52-20776.

By the way, when a photoresist is applied to the surface of a semiconductor wafer, the peripheral portion of the semiconductor wafer has a right-angled shape, so that the surface tension of the photoresist tends to cause the photoresist film to rise up in the peripheral portion.
If there is this bulge, it may not be possible to bring the mask into close contact with the photoresist, or a defect such as peeling may occur when the semiconductor wafer is transported, so it is necessary to remove it. Of the above excitement,
As shown in FIG. 3, the swelling (3) in the peripheral portion of the semiconductor wafer (1) other than the orientation flat (2) can be easily removed by spraying a resist solvent by, for example, a rotary spinner method. However, the swelling (4) of the orientation flat (2) portion which is the cutout portion of the semiconductor wafer (1) is difficult to use in the above-mentioned rotary spinner method, and tends to remain without being removed.

(Problems to be Solved by the Invention) When the above-mentioned semiconductor wafer is ashed by the above-mentioned ashing apparatus, the processing action is performed at the same speed over the entire surface of the semiconductor wafer. Therefore, for example, a resist film in a region other than the orientation flat portion is processed. If the processing operation is stopped at the time when is removed, some of the resist film in the orientation flat portion having a large film thickness remains without being removed.

On the other hand, if it is attempted to remove the resist film in the orientation flat portion as well, it may take a long time for ashing and may damage the underlying film in other regions.

Therefore, in reality, the resist film left after the ashing process is removed in the wet cleaning process.

The present invention has been made in response to the above conventional circumstances,
It is intended to provide an ashing method capable of removing a resist film within the same time over the entire area of a semiconductor wafer.

[Structure of Invention]

(Means for Solving the Problems) The present invention is a method of flowing ashing gas to a substrate to be processed to perform ashing treatment, in which the ashing gas is irradiated at a predetermined flow rate over the entire surface of the substrate to be processed. A predetermined portion of the substrate to be processed is irradiated with an ashing gas at a predetermined flow rate higher than the predetermined flow rate to process the substrate to be processed.

(Operation) The present invention irradiates the entire surface of the substrate to be processed with the asig gas at a predetermined flow rate, and irradiates the predetermined portion of the substrate to be processed with the ashing gas at a predetermined flow rate higher than the predetermined flow rate. By processing the processed substrate, even if the processed substrate has a thick portion to be processed, the processed surface can be uniformly processed in the same processing time as other portions.

(Examples) Examples of the ashing method of the present invention will be described below with reference to the drawings.

In the processing chamber (11), there is arranged a mounting table (13) for sucking and holding a substrate to be processed, for example, a semiconductor wafer (12) by a vacuum chuck or the like. The mounting table (13) includes a heater (15) controlled by a temperature control device (14), and is vertically movable by an elevating device (16).

Above the mounting table (13), for example, a cone-shaped cone portion (17) and a large number of outflow holes (18) arranged in the opening portion of the cone portion (17) are provided, and a burned material such as metal or ceramic is formed. A gas outflow part ( 20 ) composed of a diffusion plate (19) made of a unit is arranged.

In addition, near the position of the diffusion plate (19) facing the orientation flat portion (21) of the semiconductor wafer (12),
A gas outflow nozzle (22) configured to outflow gas along the orientation flat portion (21) is provided.

In addition, the cooling pipe (23) is arranged so as to surround the cone portion (17) in the gas outflow portion ( 20 ), and the cooling water (circulation) circulated through the cooling pipe (23) from the cooling device (24) may be used as necessary. Is cooled accordingly.

Further, the gas outflow portion ( 20 ) is connected to the gas flow rate controller (25) in the upper portion of the cone section (17), and the gas flow rate controller (26) communicates with the gas outflow nozzle (22). The supply pipe (27) is fixed. Furthermore, the gas flow rate controllers (25) and (26) are connected to an ozone generator (29) connected to an oxygen supply source (28).

In the lower part of the processing chamber (11), a plurality of exhaust ports (30) having a diameter of, for example, about 10 to 15 mm are arranged so as to surround the mounting table (13), and these exhaust ports (30) are gathered. An exhaust unit ( 33 ) including an exhaust pipe (32) connected to the exhaust device (31) is provided.

Next, the ashing method will be described.

First, the mounting table (13) is lowered by the elevating device (16), and a space for introducing an arm or the like of a wafer transfer device (not shown) is provided between the semiconductor wafer (12) and the gas outlet ( 20 ). ) Is mounted on the mounting table (13) by this wafer transfer device or the like and is suction-held. Then, the mounting table (13) is raised by the elevating device (16), and the distance between the diffusion plate (19) of the gas outflow portion ( 20 ) and the surface of the semiconductor wafer (12) is set to, for example, 0.5.
Set so that the specified interval is about 20 mm. In addition,
In this case, the gas outflow part ( 20 ) may be moved up and down by a lifting device.

In addition, the heater (15) built in the mounting table (13) is controlled by the temperature control device (14) to move the semiconductor wafer (12) to 15
Heat to a range of 0 to 500 ° C.

Next, the flow rate of the oxygen gas containing ozone supplied from the oxygen supply source (28) and the ozone generator (29) is adjusted by the gas flow rate controller (25), and the semiconductor wafer (12) is discharged from the gas outflow section ( 20 ). ) To irradiate. At the same time, the flow rate is adjusted by the gas flow rate controller (26), and the gas is emitted from the gas outflow nozzle (22) toward the orientation flat portion (21) of the semiconductor wafer (12) through the gas supply pipe (27).

Further, by adjusting the exhaust amount of the exhaust device (31), the processing chamber (11)
The gas pressure in the vicinity of the ashing surface of the semiconductor wafer (12) is evacuated so as to fall within a range of, for example, about 700 to 200 Torr.

At this time, as shown by the arrow in FIG. 2, between the gas outflow part ( 20 ) and the semiconductor wafer (12), the gas flows out from the outflow hole (18) of the diffusion plate (19) and the semiconductor wafer (12). A flow of gas toward the surroundings and a flow of gas flowing from the gas outflow nozzle (22) toward the orientation flat portion (21) of the semiconductor wafer (12) are formed.

Therefore, since a relatively large amount of ashing gas can be supplied to the area near the orientation flat portion (21) as compared with other areas, the ashing process is promoted, and even if the film thickness is high, it will be The resist film can be removed within the same time as the area.

The life of the ozone generated by the ozone generator (29) depends on the temperature. Generally, when the temperature rises, the decomposition of ozone is promoted and the life is drastically shortened. Then the gas outlet ( 2
0 ) is, for example, 2 by a cooling device (24) and a cooling pipe (23).
Cool to about 5 ℃ or less.

In this embodiment, the diffuser plate (19) of the gas outflow portion ( 20 ) having a large number of outflow holes (18) has been described, but the present invention is not limited to this embodiment. Alternatively, for example, a diffusion plate (not shown) made of a sintered body such as metal or ceramic may be used. Further, the gas outflow portion ( 20 ) may be configured to perform gas outflow / outflow in the diffusion plate, in addition to the outflow of the ashing gas.

Further, the gas outflow nozzle (22) is only required to be able to irradiate a large amount of ashing gas onto the area of the orientation flat portion (21), so that the nozzle shape is not particularly limited, and for example, a square one opening or a small opening. It may be configured by arranging a plurality of the above.

In short, it suffices if the specific region can be irradiated with a larger amount of gas than other regions.

Therefore, the diffuser plate (19) may be configured to have the same function as the gas outflow nozzle (22) without providing the gas outflow nozzle (22), but it is difficult to adjust the outflow amount. The method of providing the gas outflow nozzle (22) as in the present invention is preferable.

〔The invention's effect〕

According to the present invention, even if there is a portion having a large film thickness to be processed on the substrate to be processed, the processing surface can be uniformly processed in the same processing time as other parts, and the yield of the substrate to be processed can be improved. It is possible to improve the processing throughput as well as the processing throughput.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining the ashing method of the present invention, FIG. 2 is an explanatory diagram of the gas flow in the main part of FIG. 1, and FIG.
The figure is an illustration of a semiconductor wafer. 11 …… Processing chamber, 12 …… Semiconductor wafer, 19 …… Diffusion plate, 21 …… Orientation flat part, 22 …… Gas outflow nozzle.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location 7352-4M H01L 21/30 572 A

Claims (2)

[Claims] 1. A method of flowing ashing gas to a substrate to be processed to perform ashing treatment, irradiating the ashing gas at a predetermined flow rate over the entire surface of the substrate to be processed, and at a predetermined flow rate higher than the predetermined flow rate. In the ashing method, the predetermined portion of the substrate to be processed is irradiated with an ashing gas to process the substrate to be processed. 2. The ashing method according to claim 1, wherein the predetermined portion is an orientation flat portion.