JPH0370131A - Ashing - Google Patents

Abstract

PURPOSE:To make a gas flow uniform and to improve irregularity of ashing by making reaction gas flow in from a plurality of inlet ports having an opening which is made downward slightly diagonally, by forming a spiral gas flow above a treated body, by performing plasma excitation for a gas flow and by applying ashing treatment to an organic substance of the treated body surface. CONSTITUTION:Three reaction gas inlet ports are provided to an L-shaped gas inlet tube and opened slightly diagonally downward in transverse direction having different opening diameters so that reaction gas is made to flow along the sidewall of a treatment chamber in an ashing treatment chamber 3 and reaches a center gradually forming a spiral gas flow above a wafer 6. Furthermore, plasma excitation is carried out for gas flow, which receives a microwave, and the gas flow reaches the wafer 6 and reacts on a resist 61 on a wafer surface. Thereby, plasma is brought into contact with the entire surface of a wafer uniformly and ashing treatment is applied thereto. Through-put in ashing treatment can be also improved.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the ashing method, the purpose of the present invention is to make the gas flow more uniform and improve the non-uniformity of ashing. In the ashing method, a reaction gas is introduced laterally through a plurality of inlets having slightly diagonally downward openings,
The present invention is characterized in that a spiral gas flow is created above the object to be processed, and the gas flow is excited by plasma to ash the organic material on the surface of the object to be processed.

[Industrial application field]

The present invention is applied to ashing (ashing) used in photo processing, etc.
This invention relates to improvements in ashing methods.

A photo process is one of the main steps in the process of manufacturing semiconductor devices such as ICs, and at that time, a dry ashing process is performed to remove the resist. However, it is desirable that the ashing process be performed uniformly over the entire surface of the wafer, and the present invention relates to such an ashing method.

[Conventional technology]

Conventionally, as a dry ashing method for removing resist (organic material) from the surface of a wafer (object to be processed), a high frequency wave of approximately 13.56 MH2 is introduced from a high frequency power source to turn oxygen gas into plasma, and ashing is performed using the oxygen plasma. A method is used in which ashing processing is performed using oxygen plasma that is converted into microwave plasma by introducing microwaves of 2.45 GIIZ from a microwave power source.

Figure 3 shows a cross-sectional view of the main parts of a conventional ashing device applied to the microwave plasma ashing method. 0.5 is a reaction gas inlet, 6 is a wafer (object to be processed), and 7 is a wafer stage.

The processing method is to evacuate the inside of the ashing processing chamber 3 through the exhaust port 4, introduce oxygen (02) gas through the reaction gas inlet 5 to reduce the pressure inside the processing chamber to Q, l Torr to several Torr, and then use the introduced microwave. The resist 61 on the surface of the wafer 6 is removed by ashing by plasma-exciting oxygen gas. At this time, a method is generally adopted in which the ashing process is performed by uniformly flowing the reaction gas vertically toward the wafer surface from the reaction gas inlet 5, thereby making the ashing process uniform over the entire surface of the wafer. ing.

Note that, in addition to oxygen (02) alone, the reaction gas may include a mixture of oxygen gas, carbon tetrafluoride (freon, CF), and nitrogen (N2) in order to increase throughput.

[Problem to be solved by the invention]

By the way, in the ashing method using the conventional ashing apparatus as shown in FIG. 3, in order to perform the ashing process uniformly, the reaction gas is caused to flow vertically toward the 6 surfaces of the wafer, as described above. However, recently, as the equipment itself has been improved and the power of high-frequency power sources and microwave power sources has become stronger, and the plasma excitation efficiency has improved, it has become difficult to uniformize the ashing process over the entire surface of the wafer. This did not pose much of a problem with conventional processing methods, which had poor plasma excitation efficiency and required long processing times, but if the plasma excitation efficiency improved and it became possible to perform short processing times with high throughput, it would be possible to It seems that the non-uniformity of the gas flow has become apparent.

The present invention proposes an ashing method that aims to improve the non-uniformity of ashing by making the gas flow more uniform.

[Means to solve the problem]

The problem is that, as shown in FIG.
The problem is solved by an ashing method in which a reactive gas is introduced from 3 to create a spiral gas flow above the object to be processed 6, and the gas flow is excited with plasma to ash the organic substance 61 on the surface of the object to be processed. be done.

[For production]

That is, in the present invention, a spiral gas flow is created in the ashing processing chamber, and the flow is excited by plasma to react with the organic material (resist) 61 of the object to be processed (wafer). In this way, the plasma can react more uniformly on the wafer surface than in the past, and the wafer can be processed more uniformly.

〔Example〕

Examples will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part of an ashing device to which an ashing method according to the present invention is applied, and FIG. 2 is a perspective plan view of FIG. 1. The symbols in the figure are common to both figures, ■ is a microwave inlet, 2 is a microwave transmission window, 3 is an associating processing chamber, and 4 is an exhaust port.

6 is a wafer, 7 is a wafer stage, 51.52°, 53 is a reaction gas inlet, and 61 is a resist.

In this example, three reactive gas inlets are provided in the L-shaped gas inlet pipe, and the openings are opened slightly diagonally downward and laterally, and the diameter of each opening is changed, so that the reactive gas flows inside the ashing processing chamber 3 along the side wall of the processing chamber. The gas flow gradually reaches the center so that the gas flow forms a spiral above the wafer 6. During this time, the plasma is excited by receiving microwaves, reaches the surface of the wafer 6, and reacts with the resist 61 on the wafer surface. By doing so, the plasma uniformly contacts the entire surface of the wafer and performs the ashing process, thereby improving the throughput of the ashing process.

To explain a specific example of the ashing method, a wafer to be processed with a diameter of 5 inches is accommodated in an ashing processing chamber with a diameter of 10 inches, and an oxygen gas of 0.5 to 3. O1! The ashing processing chamber is injected with microwaves to create a plasma state and perform processing while maintaining the degree of vacuum at I Torr by inflowing the ashing chamber. In this case, the film thickness will be 3.0 with a processing time of several minutes.
It was possible to uniformly remove resist with a thickness of ~3.2 μm. Therefore, according to the present invention, it is possible to improve throughput and improve the quality of objects to be processed.

Note that although the above example has been explained using an ashing method using microwave excitation, it is of course applicable to an ashing method using high frequency excitation.

〔Effect of the invention〕

As is clear from the above description, the ashing method according to the present invention improves the throughput of the ashing process, and also contributes to high reliability of the object to be processed.

[Brief explanation of drawings]

FIG. 1 shows an example of an application to which the ashing method according to the present invention is applied.
FIG. 2 is a perspective plan view of FIG. 1, and FIG. 3 is a sectional view of essential parts of a conventional ashing device. In the figure, 1 is a microwave inlet, 2 is a microwave transmission window, 3 is an ashing processing chamber, 4 is an exhaust port, 5, 5L 52.53 is a reaction gas inlet, 6 is a wafer 7 is a wafer stage, 61 is a resist It shows. ! ! 1 Figure 3 of the cross-section of 17 Tsushiyu 7 and E1 Ba! I! 2 Figure

Claims (1)

[Claims] In an ashing method for ashing an organic substance by plasma excitation of a reactive gas, the reactive gas is introduced from a plurality of inlets having slightly downwardly diagonal openings in the lateral direction, and the reactive gas is injected into the upper part of the object to be processed. An ashing method characterized in that a spiral gas flow is created and the gas flow is excited with plasma to ash the organic material on the surface of the object to be processed.