KR100217816B1 - Measuring method and its apparatus of end point of dry etching - Google Patents

Abstract

The present invention relates to a dry etching end time measurement method and apparatus, and more particularly, to an electrical change value measurement method for measuring an electrical transition of a measurement element having characteristics of fluctuating electrical signals as etching of a target material progresses; An etch end time determination step of inputting the electrical change value as data that can be read by the microprocessor and providing the microprocessor with data on the design area, thickness, density, and etch rate of the target material to be etched, And a display and control process of displaying the etching state of the target material on the display unit and controlling the etching operation by the microprocessor, and a device for implementing the method.

Since the etching process can be performed very easily and the etching thickness of the target material can be exactly matched with the designed numerical value, the present invention can improve the production efficiency and increase the production yield of the product, It is effective.

Description

Dry etching end point measurement method and apparatus

FIG. 1 is a view showing a configuration of a conventional dry etching apparatus. FIG.

FIG. 2 is a view showing a configuration of a dry etching end time measurement apparatus according to the present invention; FIG.

FIG. 3 is a block diagram of the dry etching end time measurement apparatus of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

1: chamber 2: electrode

5: substrate mounting table 6: electrode

12: outlet 13: substrate

20: crystal oscillator 30: frequency measuring unit

40: voltage measurement unit 50: analog / digital conversion unit

60: Microprocessor

70: Display unit 80:

The present invention relates to a dry etching end time measurement method and apparatus, and more particularly, to a dry etching end time measurement method and apparatus for precisely controlling an etching end point in a reporter amount using a crystal oscillator .

Generally, in the dry etching process, the state of the plasma varies depending on the conditions such as the temperature and the humidity, and the state of the plasma is represented by the etching rate difference of the dry etching apparatus.

The conventional dry etching apparatus has a problem that it is very complicated and troublesome because a lot of experiments have to be performed beforehand in order to determine the exact end point of the etching. Further, since it is difficult to know the exact end point of etching by instantaneous random change, , And the overburden ratio is increased due to the over-etching.

1 shows a structure of a conventional dry etching apparatus. As shown in the figure, an electrode 2 is provided in an upper part inside the chamber 2, a tuning network part 3 is connected to the electrode 2, And the high frequency applying device 4 is connected to the tuning network 3.

A base mounting base 5 and an electrode 6 are provided on the inner lower side of the chamber 1 and a tuning network portion 7 is connected to the base mounting base 5. A high frequency applying device 8) are connected.

A reaction gas supply device 9 is coupled to one side of the chamber 1.

A gas flow meter 10 for controlling the reaction gas supply rate is coupled to the reaction gas supply device 9 and a pressure gauge 11 is coupled to one side of the chamber 1.

In FIG. 1, reference numeral 12 denotes a discharge port, and reference numeral 14 denotes a polymer layer which is laminated inside the chamber 1 as the etching operation proceeds.

As is well known, in the conventional dry etching apparatus shown in FIG. 1, a base material 13 to be etched is coupled, inner air is exhausted through a discharge port 12 even if a predetermined degree of vacuum is maintained therein, When a high frequency is applied to the upper and lower electrodes 2 and 6 by supplying the reaction gas in the chamber 9 and the upper and lower high frequency applying devices 4 and 8 to form plasma in the chamber 1 The substrate 13 is etched.

However, according to the conventional dry etching apparatus, even if the optimum working conditions are set after performing many experiments before the operation and the etching operation is advanced, the plasma state changes as the temperature, humidity, and other conditions change from day to day. It is very difficult to judge the exact end point of the etching. As a result, when the over etching occurs and the lower layer is thin, there is a defect that the bottom layer short occurs due to the overexposure angle.

In addition, since it is difficult to determine the exact end point of etching in the past, there is a problem that the etching operation becomes complicated and the yield rate is lowered.

The present invention has been made in order to solve the above-mentioned conventional defects, and it is an object of the present invention to accurately control the etching end point by the electrical signal fluctuation value of the measuring element having the property of fluctuating the electrical signal as the etching of the object material progresses, And to provide a dry etching end point measurement method and apparatus therefor which can increase the yield of production.

According to an aspect of the present invention, there is provided a method of measuring an electrical characteristic of a measuring device, the method comprising: measuring an electrical conversion value of a measuring device having characteristics of fluctuating electrical signals as an object is etched; Determining an etching end time point by providing the microprocessor with data on the design area, thickness, density, and etch rate of a target material to be etched; determining an etching end time point by the microprocessor; And a display and control process of displaying the etching state on the display unit and controlling the etching operation.

In this case, the electrical fluctuation measuring element may be a quartz crystal oscillator. In this case, a frequency measuring step of measuring the frequency of the quartz oscillator, a voltage measuring step of measuring a voltage change in accordance with the frequency variation, An analog / digital conversion step of converting the digital signal into a digital signal, and an etching end time determination step of determining the etching end point by providing the digital signal to the microprocessor.

The etch end time determination process is determined by the microprocessor by measuring the resonant frequency ∇f of the quartz crystal resonator.

Wherein K; A constant for the cutting direction of the crystal oscillator crystal, K _l ; The ratio of the re-sputtering on the entire amount of etching toen (Mt) amount (Mrs), K _2; The ratio of the amount repressed on the crystal oscillator in the amount of residual sputtered in the chamber, 5K ₃ ; The etching rate of the target material with respect to the etching rate of the photoresist, Ap; The area occupied by the photoresist, Am; The area occupied by the target substance, Dp; Density of photoresist, Dm; Represents the density of the substance of interest.

According to another aspect of the present invention, there is provided a frequency synthesizer including frequency measurement means for measuring a frequency of a crystal oscillator, voltage measurement means for measuring a voltage change according to the frequency change, analog / digital conversion means for converting an analog signal according to the voltage change into a digital signal And a dry etching end point measuring device.

The crystal oscillator is installed in a middle region between a substrate mounting base for applying a bias to the substrate and an area of the electrode and an outlet area to which the pumping force directly responds, thereby increasing the accuracy of the measured value.

The present invention provides an advantage that a target material can be etched very accurately when a semiconductor wafer or the like is etched.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 2 is a diagram showing a configuration of the present invention apparatus. As shown in FIG. 2, an electrode 2 is provided inside the chamber 1, a tuning network 3 is connected to the electrode 2, A high-frequency applying device 4 is connected to the tuning network 3.

A base mounting base 5 and an electrode 6 are provided on the inner lower side of the attachment 1 and a tuning network portion 7 is connected to the base mounting base 5. A high frequency applying device 8) are connected.

A reaction gas supply device 9 is coupled to one side of the chamber 1.

A crystal oscillator 20 according to the present invention is coupled to one side of the tip 1 of the dry etching apparatus.

The crystal oscillator 20 is installed in the intermediate region between the substrate mounting base 5 for applying a bias to the substrate 13 and the region of the electrode 6 and the region of the outlet 12 directly acting on the pumping force.

3 is a block diagram of an apparatus for measuring the end point of dry etching according to the present invention. As shown in FIG. 3, a frequency measuring unit 30 for measuring a resonant frequency of a crystal oscillator 20, An analog / digital conversion unit 50 for converting an analog signal according to the voltage variation into a digital signal, a display unit 70 for displaying an etching state of an object material, And a microprocessor 60 for receiving data required for etching and controlling the display unit 70 and the etching apparatus system control unit 80.

The etching control operation according to the present invention is as follows.

(1) Theory of mass measurement of crystal oscillator The operating frequency of the oscillator (20) depends on the mechanical properties of crystals. Therefore, if this property changes, the frequency also changes. .

The first approximation formula between the frequency and the mass of the crystal oscillator 20 is as follows.

In the equation f; Resonant frequency, M; The total mass of the crystal and the thin film, K; The constants for the cutting direction of the crystals used, respectively, and K is a constant value when the system is kept constant.

In the above equation (1), the period P of the waveform is the inverse of the fundamental frequency, and is expressed by the following equation.

(2) Application theory in dry etching process

The dry etching process is performed after patterning by photolithography, and the surface of the wafer to be etched is composed of the photoresist and the material to be etched.

Assuming that the area occupied by the photoresist is Am and the area occupied by the target material is Am and the thickness of the photoresist to be etched after etching for a predetermined time Tp is tp and the thickness of the target material is tm, The amount of etched photoresist after photoresist is the same as in (3) and the amount of material to be etched is the same as in (4).

Therefore, the total etched amount becomes the following equation (5), which is converted to mass (6).

Where Dp is the density of the photoresist, and Dm is the density of the target material.

Then, the etched photoresist and a part of the object material are discharged through the discharge port 12 by the pumping force of the pump, and a part of the photoresist and the object material are resputtered and remain in the chamber 1.

In this case, if the ratio of the reputtered amount (Mrs) to the total etched amount (Mt) is K ₁ , then K ₁ differs from one system to another. In a repetitive operation in one system, It shows almost constant value.

Therefore, the amount repressed with respect to the entire surface of the chamber 1 is equal to the following expression (8).

On the other hand, if the ratio of re-sputtering amount in the chamber 1 remains crystal oscillator (20) Li of the sputtering amount in the LA K _2, K ₂ are in accordance with the distance from the crystal oscillator 20 in the substrate 13, If the distance is kept constant, that is, the position of the crystal oscillator 20 is fixed, K ₂ shows a constant value.

Therefore, the amount repressed on the crystal oscillator 20 becomes as shown in the following equation (9).

This is the mass corresponding to ∇M in equation (2) above. Therefore, substituting this into Eq. (2) results in Eq. (10).

The etching rate Ep = tp / T of the photoresist, the etching rate Em = tm / T of the target material, and the etching selectivity S = Em / Ep satisfy the following equation (11).

Substituting equation (10) into equation (9) results in equation (12).

Wherein _{K, K l, K 2,} K 3 are constant and the constant Dp, Dm is a characteristic of known materials Ap, Am is wherein any of the preceding tm measurable area takes a value of a certain constant inversely related. In other words, all the terms before 0 have no terms that are variable during etching.

Therefore, if ∇P = 1 / ∇f is measured with respect to the crystal oscillator 20, the etching thickness tm of the target material can be measured by the following equation (13).

(3) Actual application method

① Perform basic experiments 2-3 times before actual work. , And the etching rate of the photoresist to be used and the etching rate of the target material are measured to calculate K ₃ .

(2) Calculate Ap and Am by calculating the area occupied by the photoresist and the area occupied by the target material on the design drawing.

③ Measure ∇f by the crystal oscillator (20).

④ Determine the etch thickness (tm) of the target material by substituting the known densities Dp and Dm of each photoresist and the target material and the respective factors into the above equation (12).

⑤ And once measured in one system And, Dp, Dm is always constant because the different target materials etching when there by design drawing Ap, after determining the Am ask K ₃ only by the pilot method easily determines the etching thickness of the target material accurately etch the end of the substance Can be managed.

The present invention as described above has an advantage that it is possible to reduce the basic experiment according to the etching since the accurate etching thickness can be determined by the basic experiment about 2-3 times.

In addition, since it is possible to accurately measure the etching thickness, there is an advantage that the etching end point can be easily determined.

In addition, since the factor for measuring the etching thickness of a target material is a constant term, the numerical value is defined as linear data, so that there is an advantage that the etching process can be promptly performed even for the change of the power source and the gas flow rate.

In addition, if only one constant of the target substance is defined, there is an advantage that the etching process for the same material can be carried out without an initial experiment.

As a result, the present invention can perform the etching process very easily, and the etching thickness of the target material can be exactly matched with the designed numerical value, so that the production efficiency is improved and the production yield of the product is increased, It is effective.

Claims (7)

A step of measuring an electrical conversion value of a measuring device having a characteristic that an electric signal varies as the etching of a target material proceeds; a step of inputting the electrical variation value as data decodable in a microprocessor, An etching end point determination step of providing data on the design area, thickness, density, and etching rate of the material to the microprocessor to determine an etching end point; And displaying and controlling the etching operation of the target material on the display unit by the microprocessor. The method of claim 1, further comprising: measuring a frequency of the crystal oscillator installed at one side of the chamber; A voltage measuring step of measuring a voltage change according to the frequency change; An analog / digital conversion step of converting an analog signal according to the voltage variation into a digital signal; And determining an etch end time point by providing the digital signal to the microprocessor to determine an etch end point. 3. The method of claim 2, wherein the step of determining the etch end time by the microprocessor comprises the step of measuring the resonant frequency of the quartz crystal in the frequency measurement step, The dry etch end time measurement method comprising: Wherein K is a constant for the cutting direction of the crystal oscillator crystal, K ₁ is a ratio of the reputtered amount (Mrs) to the total etched amount (Mt), K ₂ is a ratio the density of the photoresist; ratio of the in-phase crystal oscillator Li sputtering amount, K _3; etch rate of the target material to the etch rate of the photoresist, Ap; area of photoresist which accounts, Am; area of the substance occupies, Dp Dm is the density of the target substance. A measurement element provided at one side of the chamber and having a characteristic that the electric signal varies as the etching of the target material proceeds; An electrical change value measuring means for measuring an electrical conversion value of the measuring element; Data conversion means for converting the electrical change value into data that can be read by the microprocessor; Display means for displaying an etching state of the target material; And a microprocessor for receiving the data inputted by the data converting means and the data on the design area, thickness, density and etch rate of the target material, determining the etching end point, and controlling the etching operation. Apparatus for measuring end point of etching. The dry etching end time measurement apparatus according to claim 4, wherein the electrical fluctuation value measuring means is a crystal oscillator installed on one side of the chamber. The frequency synthesizer according to claim 5, further comprising: frequency measuring means for measuring a frequency of the crystal oscillator; Voltage measuring means for measuring a voltage change according to the frequency change; And an analog / digital conversion means for converting an analog signal according to the voltage variation into a digital signal. The dry etching method according to claim 5 or 6, wherein the crystal oscillator is installed in a middle region between a substrate mounting base for applying a bias to the substrate and an area of the electrode and a discharge area to which the pumping force directly acts. Point measuring device.