JPH1164287A - Method for sensing damage state of resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately sense damage state of resist by measuring component of outgas discharged from the resist by a mass analyzer, and sensing the damage state of the resist according to an amount of resist decomposed component contained in the outgas. SOLUTION: A mass analyzer 24 is mounted on a wall surface of a vacuum container 2. Resist on a surface of a substrate 6 contains, for example, cyclized rubber, polycinnamic acid, novolac resin and the like as main components, all of which contain organic component. When such a resist is damages owing to temperature rise in the case of irradiation with an ion beam, an amount of resist decomposed component contained in outgas discharged from the resist is increased. Then, components of the outgas discharged from the resist on the surface of the substrate 6 are measured by the analyzer 24. And, damage state of the resist is directly sensed by an amount of resist decomposed component contained in the outgas measured. It can be accurately sensed to improve reliability of the sensing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating a substrate having a resist on its surface with an ion beam in a state where the substrate is attracted and held by an electrostatic chuck to perform ion implantation, ion beam etching, thin film formation, etc. The present invention relates to a method for detecting a damaged state of a resist due to a rise in the temperature of a substrate during processing.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing an example of a conventional ion beam irradiation apparatus. In this apparatus, an electrostatic chuck 10 is provided in a vacuum vessel 2, and a substrate (eg, a semiconductor wafer) 6 held by suction is irradiated with an ion beam 4 to perform ion implantation, ion beam etching, thin film formation, and the like on the substrate 6. Is performed.

The inside of the vacuum vessel 2 is evacuated to a vacuum by a vacuum exhaust device (not shown). The ion beam 4 is extracted from an ion source (not shown), and mass separation,
The substrate 6 is irradiated after acceleration, scanning and the like are performed. On the surface of the substrate 6, for example, as shown in FIG. 5, a resist 8 having a required pattern is formed.

The electrostatic chuck 10 is of a so-called bipolar type in this example, and has two electrodes 14 and 16 embedded near the surface in an insulator 12. The electrodes 14 and 16 are, for example, both semicircular and are arranged so that they face each other and form a circle.

The substrate 6 is supplied onto the electrostatic chuck 10 and a voltage (in this example, a DC voltage + V of the same value but opposite polarity in this example) is applied to the electrostatic chuck 10 (more specifically, the electrodes 14 and 16 thereof) from the power supply 18 for suction. And −V), positive and negative charges are accumulated between the substrate 6 and the electrodes 14 and 16, and the electrostatic force (or Johnson-Rahbek force) acting therebetween causes the substrate 6 to be attracted and held on the electrostatic chuck 10.

The substrate 6 on the electrostatic chuck 10 receives a heat input by the irradiation of the ion beam 4. In that case, if the substrate 6 is correctly attracted to the electrostatic chuck 10, the heat applied to the substrate 6 is carried away via the electrostatic chuck 10, that is, the substrate 6 is cooled by the electrostatic chuck 10. Therefore, although the temperature rise of the substrate 6 and thus the resist 8 on the surface thereof can be suppressed, if the suction state of the substrate 6 is poor, the cooling state of the substrate 6 deteriorates and the temperature rise of the resist 8 becomes excessive. If the temperature rise of the resist 8 becomes excessive,
The resist 8 is damaged by heat and causes, for example, deterioration, deformation and the like.

In order to prevent this, as shown in FIG. 4, the capacitance between the electrodes 14, 16 of the electrostatic chuck 10 and the substrate 6 is measured by a capacitance meter 22, and the capacitance is measured. A method of detecting the suction state of the substrate 6 on the electrostatic chuck 10 according to the size of the
A method has already been proposed in which a leakage current between the electrodes 4 and 16 is measured, and the state of adsorption of the substrate 6 to the electrostatic chuck 10 is detected based on the magnitude of the leakage current. For example, the method is described in JP-A-4-216650, and the method is described in JP-A-59-79545.

[0008]

However, in the above method, the suction state of the substrate 6 is indirectly detected by measuring the capacitance or the leakage current, and further, the resist 8 on the substrate 6 is detected by the suction state. Since the temperature is estimated and the damage of the resist 8 is estimated, and the damage state of the resist 8 which is the final purpose is not directly detected, the distance between the measured amount and the damage state of the resist 8 is not detected. Therefore, there is a problem that the damaged state of the resist cannot be accurately detected.

For example, in the above-described method for measuring the capacitance, the measurement result changes depending on the type of the substrate 6 and the like. For example, in the case of the substrate 6 having a high dielectric film on the surface, the high dielectric film causes an increase in capacitance. Quantitation may be obtained. In addition, doped polysilicon (p-
In the case of the substrate 6 having an Si) film on the surface, the film comes into contact with a conductor portion provided near the surface of the electrostatic chuck 10 to cause an increase in capacitance, and a predetermined adsorption performance is obtained. Even if not provided, a predetermined amount of capacitance may be obtained.

In the method of measuring the leakage current, the measurement result varies depending on the type of the substrate 6 and the like. For example, a substrate 6 having an oxide film (for example, SiO ₂ film) on its surface
In this case, even if the substrate 6 is correctly adsorbed, the leakage current does not increase due to the presence of the oxide film, and the adsorbed state may not be detected correctly.

Accordingly, it is a primary object of the present invention to provide a method capable of accurately detecting a damaged state of a resist on a substrate surface.

[0012]

A detection method according to the present invention comprises:
When a substrate having a resist on its surface is adsorbed and held on an electrostatic chuck, the substrate is irradiated with an ion beam to perform a process, and a component of an outgas released from the resist is measured by a mass spectrometer. The method is characterized in that the damaged state of the resist is detected based on the amount of a resist decomposition component contained therein.

If the resist on the substrate surface is damaged by the temperature rise, the amount of the resist decomposition component contained in the outgas released from the resist with the irradiation of the ion beam increases. Therefore, the components of the outgas can be measured by a mass spectrometer, and the amount of resist decomposing components contained in the outgas can directly and accurately detect the damage state of the resist.

[0014]

FIG. 1 is a diagram showing an example of an ion beam irradiation apparatus for implementing a detection method according to the present invention. Parts that are the same as or correspond to those in the conventional example of FIG.

In this apparatus, a mass spectrometer 24 for measuring a component of outgas released from a resist 8 (see FIG. 5; the same applies hereinafter) on the surface of the substrate 6 upon irradiation of the ion beam 4 is connected to a vacuum vessel. 2 attached to the wall. The mass spectrometer 24 is a device that analyzes the type of gas molecule by its mass. Specifically, this example is a quadrupole mass spectrometer that performs a mass analysis by forming a quadrupole electric field with a quadrupole electrode. Note that the capacitance meter 22 and the capacitor C provided in the conventional example are omitted in this example.

The resist 8 on the surface of the substrate 6 is mainly composed of, for example, cyclized rubber, polycinnamic acid, novolak resin, etc., and all of them contain organic substances.

If the resist 8 is damaged by the temperature rise accompanying the ion beam irradiation, the amount of the resist decomposition component contained in the outgas released from the resist 8 increases. For example, the organic matter contained in the resist 8 is damaged and dissociated, and the amount (proportion) of hydrocarbon (C _x H _{y, where} x and y are positive integers) components in the outgas increases. The temperature of the resist 8 is low and before the damage, water (H ₂
O) The component is dominant.

FIG. 2 shows an example of a temporal change of an outgas component during ion beam irradiation. In this example, from around 200 seconds after the ion beam irradiation time, C ₂ H _2, which is a resist decomposition component, rapidly increases. Although the resist decomposition component (C ₂ H _{2 in} this example) is released a little when the temperature of the resist 8 rises, a large amount of the resist is released as in this example because the temperature rise of the resist 8 becomes excessive. This indicates that the resist 8 has been damaged.

Therefore, according to the present invention, the outgas component released from the resist 8 on the surface of the substrate 6 is measured by the mass spectrometer 24 as described above, and the resist decomposition component contained in the measured outgas (for example, Done C
by the amount of _x H _y), and so as to detect the damage state of the resist 8.

Thus, the damage state of the resist 8 on the substrate surface is not indirectly estimated by the capacitance or the leakage current as in the prior art, but the damage state of the resist 8 is directly detected by the amount of the resist decomposition component. Therefore, the damage state of the resist 8, which is the final purpose, can be accurately detected, and the reliability of the detection is improved.

When the damage of the resist 8 is detected as described above, for example, the processing of the substrate 6 is stopped immediately (that is, the irradiation of the ion beam) to thereby continuously process a plurality of substrates. Can be prevented from continuing.

When the irradiation of the substrate 6 with the ion beam is stopped, the heat input to the substrate 6 is stopped, so that the temperatures of the substrate 6 and the resist 8 gradually decrease, and accordingly, the amount of the resist decomposition components contained in the outgas also decreases. Decrease gradually. An example is shown in FIG. In that case, it is possible to estimate the cause of the damage to the resist 8 depending on how the resist decomposition components decrease after the stop of the ion beam irradiation. For example, as shown by a curve A in FIG. 3, a resist decomposition component (in this example, C
_{If 2} H ₂ ) decreases slowly, the electrostatic chuck 10
It can be presumed that the cooling performance for the substrate 6 is poor due to poor suction, and the temperature rise of the resist 8 becomes excessive. When the amount of the resist decomposition component decreases sharply as in the curve B, the cooling performance of the substrate 6 by the electrostatic chuck 10 is not bad, and causes other than the adsorption failure of the electrostatic chuck 10 (for example, the beam of the ion beam 4). It can be estimated that the temperature rise of the resist 8 has become excessive due to the abnormal amount or energy). Such cause estimation is impossible with the above-described conventional technology.

[0023]

As described above, according to the present invention, the damage state of the resist on the substrate surface is not indirectly estimated by the capacitance or the leakage current as in the prior art, but by the amount of the resist decomposition component. Since the damaged state of the resist is directly detected, the damaged state of the resist can be accurately detected, and the reliability of the detection is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an ion beam irradiation apparatus that performs a detection method according to the present invention.

FIG. 2 is a diagram showing an example of a time change of an outgas component during ion beam irradiation.

FIG. 3 is an enlarged view showing an example of a temporal change of C ₂ H ₂ during outgassing during ion beam irradiation and after irradiation is stopped.

FIG. 4 is a diagram illustrating an example of a conventional ion beam irradiation apparatus.

FIG. 5 is a schematic sectional view showing an example of a substrate having a resist on the surface.

[Explanation of symbols]

 Reference Signs List 4 ion beam 6 substrate 8 resist 10 electrostatic chuck 24 mass spectrometer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/265 H01L 21/265 T 21/3065 21/302 D

Claims (1)

[Claims] When a substrate having a resist on its surface is adsorbed and held on an electrostatic chuck, the substrate is irradiated with an ion beam to perform a process, and a component of outgas released from the resist is measured by a mass spectrometer. A method for detecting a damaged state of the resist, comprising measuring the amount of the resist decomposition component contained in the outgas and measuring the damaged state of the resist.