JPH0296765A - Ashing method - Google Patents

Abstract

PURPOSE:To execute high-speed ashing of a film deposited on a substrate to be treated by setting the gaseous pressure near the surface of the substrate to be treated under an ashing treatment at 1 to 10ata. CONSTITUTION:A discharge port 16 for discharging the exhaust gas after the ashing treatment from an inside reaction chamber 15 enclosed by an upper chamber 2 and a lower chamber 1 is provided to the bottom of the lower chamber 1 and is piped to a discharge mechanism 17; further, a communicating port 19 communicated with a pressure control mechanism 18 is provided to, for example, the side wall of the lower chamber 1. The gaseous pressure near the surface of the substrate 9 to be treated during the ashing treatment is set at 1 to 10ata. The density of the treating gas near the surface of the substrate 9, therefore, increases and the flow rate of the treating gas flowing along the surface of the substrate 9 near the surface of the substrate 9 decreases. The high-speed ashing is executed in this way.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an ashing method.

(Prior Art) Formation of fine patterns in semiconductor integrated circuits is generally performed by etching a base film formed on a semiconductor wafer using an organic polymer photoresist film formed by exposure and development as a mask. be exposed.

Therefore, the photoresist film used as the mask needs to be removed from the surface of the semiconductor wafer after the etching process.

Ozone (
Ashing treatment is performed using an oxidation reaction caused by 0, ), and conventional techniques include, for example, JP-A No. 52-20766 and JP-A No. 62-165923. Japanese Patent Publication No. 62-165924,
JP-A-62-165925, JP-A-62-1.6592
6. JP-A-62-165927. Japanese Patent Publication No. 62-1659
28, JP-A-62-165929, JP-A-62-165
930, JP-A-62-165931, JP-A-62-
165932. JP-A-62-165933. Unexamined Japanese Patent Publication 1986
-165934.

JP-A-62-165935, JP-A-63-32923.
JP-A-63-32924, JP-A-63-32926. JP 63-32930, JP 63-43322. Japanese Patent Publication No. 63-32927. JP-A No. 63-32928, JP-A No. 63-32925. Japanese Patent Publication No. 63-58934. Tokukai Showa 6
3-58932, JP-A-63-58933, JP-A-63
-70429, JP-A-63-81822, JP-A-63-
81823. JP-A-63-133528, JP-A-63-
133529. Some of them are disclosed in Japanese Patent Application Laid-Open No. 127537/1983.

(The problem that the invention aims to solve is 5J) However, in recent years, semiconductor wafers have tended to become larger and larger, and single-wafer processing that processes semiconductor wafers one by one, which is suitable for processing large-diameter semiconductor wafers, is desired. Therefore, in order to make this single wafer processing possible, for example, in order to improve the ashing speed, we investigated various conventional techniques. It turned out that the ashing process is performed outside the equipment at atmospheric pressure or in an even more depressurized atmosphere for reasons such as preventing certain ozone from leaking outside the equipment. flow rate)
If the pressure is kept constant, the flow rate of the ashing gas becomes faster as the pressure decreases, so it is noticed that the opportunity and time for contact between the surface of the semiconductor wafer to be processed and the ozone in the ashing gas decreases. We researched ways to increase the amount and focused on setting the processing atmosphere to high pressure.

The present invention has been made in response to the above-mentioned conventional circumstances, and provides an ashing method that enables high-speed ashing.

[Structure of the invention]

(Means for Solving the Problems) That is, in the present invention, when performing ashing processing by flowing a processing gas onto a substrate to be processed, the gas pressure near the surface of the substrate to be processed during this ashing process is set to 1 to 10 ata. It is characterized by

(Function) In the ashing method of the present invention, when performing the ashing process by flowing the processing gas onto the substrate to be processed, the gas pressure near the surface of the substrate to be processed during the ashing process is reduced to 1 to 10a.
Since it is set to ta, the density of the processing gas near the surface of the substrate to be processed becomes high, and the flow rate of the processing gas flowing near the surface of the substrate to be processed along the surface of the substrate to be processed becomes slow.

(Example) Hereinafter, an example in which the method of the present invention is applied to ashing gas in a semiconductor manufacturing process will be described with reference to the drawings.

First, the configuration of the ashing device will be explained.

Lower chamber of bottomed cylindrical aluminum (AM) 11
A useful cylindrical aluminum upper chamber is provided in the upper opening part of (■) to airtightly engage with this lower chamber (■).
■ is provided, and this upper chamber ■ is a lifting mechanism (
'5, it is configured to be vertically movable. A cylindrical nozzle (2) equipped with an outlet (0) having a diameter of, for example, about 8 m is provided near the center axis of the bottom surface of the upper chamber (2) for causing the ashing gas to flow out. A heat-resistant glass disk (2) made of an insulating material and having a thickness of about 5 m is attached to the tip of the cylindrical nozzle 0, for example.

Next, a heater (C) controlled by a temperature control mechanism (C) is built into the lower chamber (2), and a substrate to be processed, such as a semiconductor wafer (O) whose surface is coated with photoresist, is placed and heated. A plate-shaped mounting table (lO) is arranged opposite to the disk (2). Note that the mounting table (10) is provided with a suction mechanism (not shown) using a vacuum chuck, and the semiconductor wafer 0) is suction-held as necessary.

Next, on the gas supply side of the cylindrical nozzle 0, an ashing gas flow rate regulator (11), a high-pressure pump (2) that delivers high-pressure ashing gas at a constant pressure, an ozone generator (13), and an oxygen (02) A supply source (14) is connected by piping. Then, the pressure of oxygen gas containing ozone generated by the ozone generator (13) using the ashing gas, that is, the oxygen (0□) supplied from the oxygen supply source (14) as a raw material, is increased by the high-pressure pump (12), and the flow rate is adjusted. The liquid is adjusted to a predetermined flow rate by a container (11), and is configured to be able to flow out from a cylindrical nozzle (2) toward a mounting table (10).

Further, at the bottom of the lower chamber (■), an exhaust port (I
6) is provided and is piped to the exhaust mechanism (17).

Furthermore, a communication port (19) communicating with the pressure control mechanism (18) is provided in, for example, the side wall of the lower chamber (1).
The pressure control mechanism (18) measures the gas pressure in the reaction chamber (15), and based on this measurement result, for example, the exhaust mechanism (17) is controlled to adjust the exhaust amount.

Semiconductor wafer 0) Gas pressure near the surface is 1 to I Oa
ta (ata: absolute pressure per unit area lcg/aD
It is configured so that it is controlled so that.

The lifespan of the ozone generated in the ozone generator (13) depends on the temperature, and the higher the temperature, the shorter the lifespan, so the equipment piping etc. from the ozone generator (13) to the cylindrical nozzle A cooling mechanism (not shown) is provided as necessary, and the device is configured to cool to, for example, about 25° C. or lower.

Next, an ashing method using the apparatus configured as described above will be explained.

Raise the upper chamber ■ using the lifting mechanism ■.

A transport mechanism (not shown) automatically transports and places the semiconductor wafer (2) on a predetermined position on the mounting table (10) in the lower chamber ω. At this time, the semiconductor wafer ■
) can produce elements with the same characteristics with good reproducibility by performing orientation flat alignment as necessary.

Next, the upper chamber (■) is lowered by the lifting mechanism (3) and engaged with the lower chamber (■), and the inside of the reaction chamber (15) is set in a sealed state to prevent unnecessary gas leakage to the outside. . At this time, the two circular plates 0 are set at such a position that the distance between the surface facing the semiconductor wafer (2) and the surface of the semiconductor wafer 0 is, for example, about 0.5 to 20 m.

Also, at this time, the center of the outlet (a) of the cylindrical nozzle (2) is positioned on the central axis of the mounting table (10) and the semiconductor wafer (2), so that it can be uniformly distributed over the entire surface of the semiconductor wafer (2). processing is possible.

Ashing gas containing ozone generated by an ozone generator (13) using oxygen supplied from an oxygen supply source (14) as a raw material is pressurized by a high pressure pump (12).
Send it to the flow regulator (11) as a constant pressure of 10ata,
This flow rate regulator (11) adjusts the flow rate from 2 to 40S, for example.
Iil/win (SQ is the flow rate converted to normal temperature and pressure)! 51! ! The ashing gas is diffused by a diffusion plate (not shown) provided at the outlet (6) and flows out toward the surface of the semiconductor wafer 0. At this time, semiconductor wafer 0 has already been placed on the mounting table (lO
) is heated to, for example, a range of about 150 to 300°C.

Then, from above the center of the heated semiconductor wafer placed on the mounting table (10) from the outlet (a), the ashing gas, which is pressurized to a predetermined pressure and flows in 8 nodules of 1 kW, is uniformly flowed out in a radial manner. , performs an ashing process on the semiconductor wafer 0). Note that ozone is heated by the heat of the surface of the semiconductor wafer 0 to generate oxygen atomic radicals, which oxidize the photoresist and remove it as a gas.

On the other hand, the ashing gas after the ashing process is discharged by the exhaust mechanism (17) through the exhaust port (16).

During the ashing process, the pressure control mechanism (18) measures the gas pressure in the reaction chamber (I5).
! The displacement of the exhaust mechanism (17) is controlled to decrease and the pressure is increased to a predetermined pressure, and conversely, when the pressure is high, the displacement of the exhaust mechanism (17) is increased. control to lower the pressure and automatically set it to a predetermined pressure.

Here, the relationship between the pressure of the ashing gas and the ashing speed will be explained. First, when the gas pressure in the reaction chamber (15) measured by the pressure control mechanism (18) is constant,
Semiconductor wafer 0 in the reaction chamber (15) from the cylindrical nozzle ■
The amount of ashing gas flowing out toward the exhaust port (
16) to the outside of the reaction chamber (5) by the exhaust mechanism (17).

Also, if the flow rate is the same when converted to normal temperature and pressure.

The higher the pressure of the ashing gas, the more compressed the ashing gas becomes, and the higher the density of the ashing gas per unit volume.For example, when the pressure of the ashing gas is doubled, the volume is compressed to 1/2, and the ozone in this ashing gas is The sensitivity of is unchanged, but the amount of ozone present per unit volume is 2
Double.

On the other hand, the flow rate of the ashing gas, that is, the moving speed of the ashing gas from the center to the outer circumferential direction from the surface of the semiconductor wafer (2) in this example, may be slowed down as the pressure increases, for example, when the pressure is doubled. To become and,
The flow rate becomes 1/2 slower than that at the original pressure.

From the above, as the pressure of the ashing gas increases, the amount of ozone per unit volume increases and the flow rate of the ashing gas decreases, so the average contact between ozone and the photoresist film deposited on the surface of the semiconductor wafer 0 increases. As a result, the frequency at which ozone molecules collide with the resist constituent molecules on the surface of the photoresist film increases, and the oxidation effect of the photoresist film by ozone is carried out effectively, increasing the ashing rate. It is understood that it will improve.

For example, as shown in FIG. 2, the ashing speed considered necessary for single wafer processing is 1. High-speed ashing of n/sin or higher is possible. In addition, in the figure, the ashing speed increases almost in proportion to the pressure up to around aata, but
In the range exceeding 3ata, the ashing rate does not increase at the same rate as the pressure increases, and becomes saturated. This is because if the pressure rises too much, the density of ozone becomes excessive and it becomes difficult to move, so there is a limit to the number of ozone that can come into contact with the photoresist film, and the exhaust speed of waste gas generated by the oxidation reaction becomes too slow. This is because the reaction is suppressed.

In addition, when the pressure increases, the structure of the device must be able to withstand the high pressure, and there are also issues such as safety, design technology, and manufacturing costs, so the upper limit of the pressure inside one reaction chamber is 1.
．． The limit is about 0 ata, and in practical terms 4 at
The effectiveness of the method of the present invention can be maximized by carrying out the treatment within a range of about a or less.

Note that the ashing gas discharged by the exhaust mechanism (17) is decomposed by an ozone decomposer (not shown).

When the ashing process of the semiconductor wafer (■) is completed, the pressure in the reaction chamber (15) is returned to atmospheric pressure by controlling the flow rate regulators (1, 1), exhaust mechanism (17), etc., and the upper chamber is moved by the lifting mechanism (■). −■ is raised, and the semiconductor wafer ■ that has undergone the above processing is transported to the next process by a transport mechanism (not shown), and the t-conductor wafer ■ to be processed next is carried in and set on the mounting table (10). do.

Then, the above process is repeated.

Incidentally, in the above embodiment, the material of the disk (3) was explained as being made of glass, but any heat-resistant glass may be used, for example, quartz glass may be used.

Further, although the case where the ashing target is a photoresist film has been described, it can be applied to, for example, the removal of ink and various solvents, and any ashing target may be used as long as it can be removed by oxidation.

Furthermore, the ashing gas is not limited to the above-mentioned oxygen gas containing ozone, but also gases that do not react with ozone, such as N2.
, Ar, Ne, etc., containing ozone can be used.

In the above embodiments, the embodiments are applied to the processing of semiconductor wafers, but the ashing process can be applied to any photomask provided on a glass substrate, a printed circuit board, an amorphous silicon film to be deposited, etc. .

〔Effect of the invention〕

As described above, according to the present invention, it is possible to perform high-speed ashing of a film deposited on a substrate to be processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ashing apparatus in the ashing method of the present invention, and FIG. 2 is a graph showing the relationship between the reaction gas pressure and the ashing rate in FIG. 1. 1... Lower chamber 6... Disc 10... Mounting table 12... High pressure pump I8... Pressure side e1 mechanism

Claims (1)

[Claims] An ashing method characterized in that, when ashing is performed by flowing a processing gas onto a substrate to be processed, the gas pressure near the surface of the substrate to be processed during the ashing process is set to 1 to 10 ata.