JPS62272538A - Plasma processor - Google Patents

Abstract

PURPOSE:To remove a resist in a plasma processor by removing a modified layer on the surface of the resist, then switching the power of a microwave to a small value to remove the modified layer similarly to the prior art, and reducing the damage of a sample part except the resist as small as possible. CONSTITUTION:A spectrochemical analyzer 14 has a band pass filter for passing only a light having a specific wavelength varying in its intensity according to the cases when a modified layer exists or does not exist on a resist, and a photodetector for detecting the spectrum of a light from the filter, and generates a detection signal of a level responsive to the variation in the intensity of an emitting light spectrum of the specific wavelength generated from a plasma 10. A comparator 15 controls to generate a microwave having the same large power as that at the time of starting a plasma process when the input detection signal level is lower than a reference signal level (a modified layer 2 remains on the resist 1) and to generate an input detection signal level large than the reference signal level near the time when the layer 2 is removed to be finished on the resist 1. Thus, the power of the output microwave can be controlled to be switched to small power.

Description

[Detailed Description of the Invention] a. Detailed Description of the Invention [Summary] The present invention provides a plasma processing apparatus using microwaves, in which the power of the microwaves is switched to a small value after removing the degraded layer on the resist. The present invention relates to a plasma processing apparatus that removes a degraded layer and a resist while minimizing damage to a sample.

[Industrial application field]

The present invention relates to a plasma processing apparatus using microwaves, and particularly to a plasma ashing apparatus for removing resist.

After processing the base using the resist as a mask, ashing (ashing) is performed in oxygen plasma to remove unnecessary resist.

Some of these plasma processing apparatuses use short wavelength microwaves (for example, 2.4
Plasma processing apparatuses using microwaves have been known in the past, which can perform more efficient discharge and faster plasma processing by using 5 GHz) due to higher electron density.

[Conventional technology]

In a conventional plasma processing apparatus, microwaves are introduced into a vacuum plasma emission chamber through a waveguide and a transmission window sequentially, and plasma is generated under oxygen gas pressure in the plasma emission chamber. As a result, the resist on the sample is removed by activated ions and the like.

According to this plasma processing apparatus using microwaves, as shown in FIG. 4, even if a degraded layer 2 is formed on the surface of the resist 1 that has been implanted with high-concentration ions, the resist will be processed along with the degraded layer 2. 1 can be peeled off.

[Problem that the invention seeks to solve]

In the above conventional plasma processing apparatus, the above resist 1
In order to remove the deteriorated layer 2, plasma was generated using microwaves of large value and constant power.

However, due to the generation of energetic charged particles,
Various types of irradiation damage occur, and as shown in FIG. 3, as the power increases, the amount of damage (amount of irradiation damage) on the sample surface increases.

For this reason, in conventional plasma processing equipment, even after the altered layer 2 is removed, the same high power as before the removal is applied to the resist 1.
However, the surface of the sample was sometimes damaged.

The present invention was created in view of the fact that removing only resist does not require the high power required to remove a degraded layer, and an object of the present invention is to provide a plasma processing apparatus that performs plasma ashing with less damage. do.

[Means for resolving the problem]

The plasma processing apparatus of the present invention is a plasma processing apparatus that performs a predetermined process on a sample using plasma generated under a predetermined gas pressure by introducing microwaves into a plasma emitting chamber. This device is composed of a detection means for detecting the detection means, and a control means for controlling the power of the microwave from the microwave generation source based on the detection output of the detection means.

[Effect]

Microwaves generated with a certain amount of power by a microwave generation source are introduced into a plasma emission chamber through a predetermined path, and generate plasma under a predetermined gas pressure. This plasma starts a predetermined process such as resist ashing on the sample in the plasma emission chamber.

With the start of this plasma treatment, detection of the reaction process for the sample in the plasma emission chamber is started by the detection means. When the value of the detection output by the detection means reaches a predetermined constant value, the control means controls the power of the microwave from the microwave generation source to be lower than the power up to that point.

As a result, the power of the microwave is generated in a large amount of time until the value of the above-mentioned detection output reaches a predetermined constant value from the start of microprocessing. Switch to a smaller value.

(Embodiment) Fig. 1 shows a block system diagram of an embodiment of the device of the present invention. It is guided and introduced into the cavity 6.

Microwaves are transmitted through a microwave-transmitting window 7 made of a dielectric material (such as ceramics) that transmits microwaves further than the cavity 6.
and is introduced into the plasma emission chamber 8.

The inside of the plasma emission v8 is a vacuum, and for example, oxygen gas is introduced at a predetermined pressure from the gas inlet 9. In this state, the above-mentioned microwave is introduced, thereby generating the plasma 10. By generating this plasma 10, charged particles are irradiated onto the wafer 12, which is a sample, and removal of unnecessary resist on the wafer 12 is started. Note that 11 is an exhaust port.

Here, as shown in FIG. 4, the resist on the wafer 12 has an altered layer 2 formed on its surface. On the other hand, since the microwave from the microwave generation source 3 is generated with a large power necessary for removing the altered layer 2 from the start of plasma processing (ashing point), the altered layer 2 is quickly removed. removed.

By the way, in this embodiment, a quartz window 1 is provided in the plasma emission chamber 8.
3 is provided, and the plasma 1 in the plasma emission chamber 8 is
The light emitted from the spectrometer 1 passes through the quartz window 13.
4. This spectroscopic analyzer 14 includes a bandpass filter that allows only light of a specific wavelength to pass, the intensity of which varies greatly depending on whether there is a degraded layer on the resist or not, and detects the spectrum of the light from this bandpass filter. It is composed of a photodetector and generates and outputs a detection signal of a level corresponding to the intensity change of the emission spectrum of the above-mentioned specific wavelength generated from the plasma 10.

The comparator 15 is supplied with the detection signal and compares it with a reference signal level equivalent to the detection signal level obtained when the altered layer 2 is not on the resist 1, and outputs the output of the microwave generation source 3 according to the comparison result. Variable control of microwave power.

That is, when the input detection signal level is lower than the reference signal level (the altered layer 2 still remains on the resist 1), the comparator 15 generates microwaves with a power as high as that at the start of plasma processing. Since the input detection signal level becomes higher than the reference signal level near the time when the altered layer 2 on the resist 1 has been removed, the power of the output microwave from the microwave generation source 3 is
Switching control is performed to a low power that is minimally necessary to remove only resist 1 and causes as little damage as possible.

As a result, the power of the microwave from the microwave generation source 3 can be changed significantly as shown in FIG. This means that the resist can be removed while maintaining the same condition.

Note that the present invention is not limited to the above embodiments, and the method for detecting the presence or absence of the altered layer 2 on the resist 1 is as follows:
In addition to the above spectroscopic analysis method, for example, an optical reflection method using laser beam interference can be used, and in short, any means that can detect the reaction process on the wafer 12 within the plasma emission chamber 8 may be used.

〔Effect of the invention〕

As described above, according to the present invention, after the damaged layer on the resist surface is removed, the microwave power is switched to low power, so that the damaged layer can be removed in the same manner as before, and the subsequent resist For bamboo, the resist can be removed with minimal damage to sample parts other than the resist using plasma generated by low-power microwaves, which leads to improvements in device characteristics. It has the following.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a characteristic diagram for explaining power switching in the device of the present invention, Fig. 3 is a characteristic diagram of an example of the amount of damage versus power, and Fig. 4 is a characteristic diagram showing an example of damage amount. It is a sectional view explaining a layer. 1 and 4, 1 is a resist, 2 is an altered layer, 3 is a microwave source, 5 is a waveguide, 6 is a cavity, 7 is a transmission window, 8 is a plasma emission chamber, 10 is a plasma, 12 is a sample (wafer), 14 is a spectroscopic analyzer, and 15 is a comparator.

Claims (1)

[Claims] Microwaves generated by a microwave generation source (3) are input into a cavity (6) through a waveguide (5), and then from there through a window (7) into a vacuum plasma emission chamber ( In a plasma processing apparatus that generates plasma (10) under a predetermined gas pressure by introducing it into a plasma emitting chamber (8), and performing a predetermined treatment on a sample (12) in the plasma emitting chamber (8), the plasma emitting chamber (8) Detection means (13, 14) for detecting the reaction process for the sample (12) in 8), and the detection output of the detection means (13, 14) is supplied, and the value of the detection output is set to a predetermined value after the start of plasma treatment. The plasma is characterized by comprising: control means (15) for controlling the power of the microwaves from the microwave generation source (3) to be lower than the power up to that point from the time when the plasma Processing equipment.