TWI552224B - Semiconductor etching apparatus and semiconductor etching method - Google Patents

Description

Semiconductor etching device and semiconductor etching method

The present invention relates to semiconductor technology, and in particular to a semiconductor etching apparatus and a semiconductor etching method.

In a semiconductor process, a process of etching a semiconductor material generally includes a dry etching process or a wet etching process, wherein a dry etching process by etching using a plasma can effectively control an etching opening. Dimensions have become the most popular etching process.

Existing processes typically utilize a glow discharge, a radio frequency signal, a corona discharge, etc. to form a plasma. Wherein, when the plasma is formed by using the radio frequency signal, the density and energy of the formed plasma can be controlled by adjusting the parameters of the processing gas component, the frequency of the radio frequency power, the coupling mode of the radio frequency power, the air pressure, and the temperature, thereby optimizing the plasma treatment effect. . Therefore, in the conventional semiconductor etching apparatus, a radio frequency signal is generally used to form a plasma, and a bias voltage is formed on the substrate to be etched by using the radio frequency signal, so that the plasma bombards the substrate to be etched, and the substrate is to be etched. The etched substrate is subjected to an etching process.

In current semiconductor etching devices, the radio frequency signal used to form the plasma is typically a continuous radio frequency signal, and the RF signal used to form the bias voltage is a continuous radio frequency signal or a pulsed radio frequency signal. When the biased RF signal is a continuous RF signal, the plasma of the etching gas continuously etches the substrate to be etched. When the biased RF signal is a pulsed RF signal, the plasma alternately etches and deposits a polymer, which facilitates the formation of high aspect ratio vias. However, the pulse frequency and pulse of the pulsed RF signal in the prior art The duty cycle is determined, and the pulse frequency and pulse duty cycle of the RF signal are constant in each etching process.

For more information on etching devices that use RF power to form a plasma for etching, please refer to US Patent No. US7405521B2.

The problem to be solved by the present invention is to provide a semiconductor etching apparatus and a semiconductor etching method, wherein a pulsed signal output from a plasma RF power source and/or a bias RF power source in the semiconductor etching apparatus changes with time.

In order to solve the above problems, an embodiment of the present invention provides a semiconductor etching apparatus, including: a reaction chamber having a wafer stage for placing a substrate to be etched; a gas supply source for a gas is introduced into the reaction chamber; a plasma RF power source is used to plasma the gas in the reaction chamber; a bias RF power source is used to form a bias voltage on the surface of the substrate to be etched; and the plasma RF power is The RF signal output by the source and/or the bias RF power source is a pulse signal, and the pulse frequency and the pulse duty ratio of the pulse signal change with time.

Optionally, the bias RF power source includes a first RF power generator and a first RF signal generator connected to the first RF power generator, where the first RF signal generator includes a first micro a processor and a first pulse width modulation controller, the first microprocessor inputs a triangular wave of a certain frequency and a reference signal of a certain voltage to the first pulse width modulation controller, wherein the first pulse width modulation controller utilizes The triangular wave of a certain frequency and the reference signal of a certain voltage control the opening time and the closing time of the first RF power generator, wherein the frequency of the triangular wave corresponds to the pulse of the first pulse signal output by the first RF power generator The frequency, the voltage of the reference signal corresponds to the ratio of the on time of the first pulse signal to the off time.

Optionally, the plasma RF power source includes a second RF power generator and a second RF signal generator connected to the second RF power generator, where the second RF signal generator includes a second micro Processor and second pulse width adjustment a controller, the second microprocessor inputs a triangular wave of a certain frequency and a reference signal of a certain voltage to a second pulse width modulation controller, wherein the second pulse width modulation controller utilizes a triangular wave of the certain frequency and a certain The reference signal of the voltage controls the turn-on time and the turn-off time of the second RF power generator, wherein the frequency of the triangular wave corresponds to the pulse frequency of the second pulse signal output by the second RF power generator, and the reference signal The voltage corresponds to the ratio of the on time of the second pulse signal to the off time.

Optionally, the first pulse width modulation controller and the second pulse width modulation controller respectively control an on time T _on (t) and an off time of the first RF power generator and the second RF power generator according to the following formula: T _off (t), f _o (t)=1/(T _on (t)+T _off (t)), V _ref (t)=a×T _on (t)/T _off (t), wherein f _o (t) is a frequency function of the triangular wave, V _ref (t) is a voltage function of the reference signal, and a is a specific coefficient.

Optionally, the frequency of the triangular wave and the voltage of the reference signal change with time.

Optionally, the first microprocessor calculates a frequency of a triangular wave corresponding to a certain time and a voltage of a reference signal according to a frequency function of the triangular wave and a voltage function of the reference signal, and the triangular wave corresponding to the frequency and the corresponding voltage The reference signal is input to the first pulse width modulation controller, and the second microprocessor calculates the frequency of the triangular wave corresponding to the certain time and the voltage of the reference signal according to the frequency function of the triangular wave and the voltage function of the reference signal, and A triangular wave corresponding to the frequency and a reference signal of the corresponding voltage are input to the second pulse width modulation controller.

Optionally, the first microprocessor and the second microprocessor store a frequency value of a time-dependent triangular wave and a voltage value of the reference signal, and the first microprocessor and the second microprocessor pair the corresponding time. After reading the frequency value of the corresponding triangular wave and the voltage value of the corresponding reference signal, the triangular wave of the corresponding frequency and the reference signal of the corresponding voltage are input to the first pulse width modulation controller and the second pulse width modulation controller.

Optionally, the method further includes controlling the computer, and using the control computer to a microprocessor and the second microprocessor input a frequency function of the triangular wave, a voltage function of the reference signal, or input a time-dependent triangular wave frequency value and a reference signal voltage value to the first microprocessor and the second microprocessor .

Optionally, the bias RF power source is connected to the stage through the first RF matcher.

Optionally, the bias RF power source is connected to the top of the reaction chamber through a first RF matcher.

Optionally, the plasma RF power source is an inductively coupled RF power source or a capacitively coupled RF power source.

The embodiment of the invention further provides a semiconductor etching method using the semiconductor etching device, comprising: providing a substrate to be etched; introducing a gas into the reaction chamber; and a plasma RF power source for gas plasma in the reaction chamber Applying a bias voltage to the surface of the substrate to be etched; etching the substrate to be etched by the plasma of the gas to form an etched pattern, the plasma RF power source and/or bias The signal output from the RF signal output by the RF power source is a pulse signal. When the etched pattern has a first depth, the pulse signal has a first pulse duty ratio and a first pulse frequency, and the etched pattern has a second depth. The pulse signal has a second pulse duty cycle and a second pulse frequency.

Optionally, the pulse signal has a pulse frequency of less than 50 kHz, and the pulse signal has a pulse duty cycle ranging from 10% to 90%.

Optionally, the etched pattern further includes a third depth, the pulse frequency and/or the pulse duty ratio of the first pulse signal and the second pulse signal corresponding to the third depth, and the first depth and the second depth Different, thereby adjusting the sidewall morphology and etching rate of the etched pattern at different depths.

Compared with the prior art, the present invention has the following advantages: the plasma RF power source of the semiconductor etching device and/or the RF signal output by the bias RF power source is a pulse signal, and the pulse frequency and pulse of the pulse signal The duty cycle changes with time and can be instantly available as needed The density and bias voltage of the plasma in the reaction chamber are adjusted to control the exchange of plasma in the via and the reaction rate in the via, thereby facilitating control of the sidewall morphology of the via.

110‧‧‧Reaction chamber

120‧‧‧Sheet

125‧‧‧ substrates to be etched

130‧‧‧ gas supply

140‧‧‧ Plasma RF power source

141‧‧‧Second RF Matcher

142‧‧‧Inductance coil

143‧‧‧Second RF power generator

144‧‧‧Second RF signal generator

145‧‧‧second microprocessor

146‧‧‧Second Pulse Width Modulation Controller

150‧‧‧Bad RF power source

151‧‧‧First RF Matcher

153‧‧‧First RF Power Generator

154‧‧‧First RF signal generator

155‧‧‧First microprocessor

156‧‧‧First Pulse Width Modulation Controller

1 to 3 are schematic views showing the structure of a semiconductor etching apparatus according to an embodiment of the present invention.

In the prior art, the radio frequency signal forming the plasma and the radio frequency signal forming the bias voltage are usually a continuous radio frequency signal or a pulsed radio frequency signal, and the pulse frequency and the pulse duty ratio of the pulsed radio frequency signal are determined to form. The RF power source of the continuous RF signal or the RF power source of the pulsed RF signal with a pulse frequency and a constant pulse duty ratio is simple in structure. However, the inventors have found that as the size of the device is reduced, the size of the structure to be etched is also reduced, especially when an existing plasma etching process is used to form a via having a high aspect ratio. As the etch progresses, the plasma exchange in the via hole becomes slower and slower, and the density of the plasma in the via hole changes. Therefore, it is necessary to instantly adjust the density and bias voltage of the plasma in the reaction chamber to control the inside of the via hole. The exchange of plasma and the rate of reaction within the vias facilitate the control of the sidewall morphology of the vias.

Therefore, an embodiment of the present invention provides a semiconductor etching apparatus and a semiconductor etching method, wherein a plasma RF power source of the semiconductor etching apparatus and/or a radio frequency signal output by a bias RF power source is a pulse signal, and the The pulse frequency of the pulse signal and the pulse duty ratio change with time, so that the density and the bias voltage of the plasma in the reaction chamber can be instantly controlled by controlling the pulse frequency and the pulse duty ratio of the pulse signal in real time. Thus, the etching rate and the morphology of the etched pattern can be controlled.

The above described objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims.

Specific details are set forth in the following description in order to provide a thorough understanding of the invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art can make similar promotion without departing from the scope of the present invention. The invention is therefore not limited by the specific embodiments disclosed below.

An embodiment of the present invention provides a semiconductor etching apparatus. Referring to FIG. 1 , a schematic structural diagram of a semiconductor etching apparatus according to an embodiment of the present invention includes: a reaction chamber 110 having a wafer stage 120 therein. For placing the substrate 125 to be etched; a gas supply source 130, the gas supply source 130 is connected to the top of the reaction chamber 110 and a gas is introduced into the reaction chamber 110; the plasma RF power source 140 passes The second RF matcher 141 is connected to the inductor 142 disposed around the sidewall of the reaction chamber 110. The RF signal generated by the plasma RF power source 140 is used to plasma the gas in the reaction chamber 110 through the inductor 142; The power source 150 is connected to the stage 120 through the first RF matching unit 151. The RF signal outputted by the bias RF power source 150 forms a bias voltage on the surface of the substrate 125 to be etched; The RF signals output by the power source 140 and the bias RF power source 150 are both pulse signals, and the pulse frequency and pulse duty ratio of the pulse signals change with time.

In the embodiment of the present invention, the RF signals output by the plasma RF power source 140 and the bias RF power source 150 are pulse signals, and both of the pulse frequency and the pulse duty ratio of the output pulse signal can be instantly controlled. Therefore, the pulse frequency and the pulse duty ratio of the pulse signal can be changed with time. In other embodiments, the RF signal outputted by the plasma RF power source or the bias RF power source is a pulse signal, and the pulse frequency and the pulse duty ratio of the pulse signal change with time. The other output RF signal is a pulse signal with a constant pulse frequency and pulse duty cycle or a continuous RF signal.

In the present embodiment, the plasma RF power source 140 is coupled to an inductor 142 disposed around a sidewall of the reaction chamber 110 by a second RF matcher 141, which is an inductively coupled RF power source. In other embodiments, the plasma RF power source is connected to the top of the reaction chamber or the stage via a second RF matching device, and correspondingly, the top of the substrate or the reaction chamber is grounded, the top of the reaction chamber and the carrier The stage forms a capacitive coupling, and RF power is formed in the reaction chamber to plasma the gas. The corresponding plasma RF power source is a capacitively coupled RF power source.

In the embodiment, the bias RF power source 150 is connected to the carrier 120 through the first RF matching unit 151, so that the surface of the substrate 125 to be etched on the substrate 120 has a negative bias. The plasma is subjected to a negative bias to concentrate on the surface of the substrate 125 to be etched, which is advantageous for improving the etching efficiency, and when the bias voltage is large, the plasma may bombard the surface of the substrate 125 to be etched, further The etching efficiency is increased, and the negative bias voltage affects the sheath voltage formed on the surface of the substrate to be etched. In other embodiments, the bias RF power source can also be connected to the top of the reaction chamber through a first RF matcher, and the plasma is positively biased by forming a positive bias at the top of the reaction chamber. Etching is performed on the surface of the substrate to be etched.

Please refer to FIG. 2 , which is a schematic structural diagram of the biased RF power source 150 of FIG. 1 . The bias RF power source 150 specifically includes: a first RF power generator 153 and is connected to the first RF power generator 153 . a first RF signal generator 154, the first RF signal generator 154 includes a first microprocessor 155 and a first pulse width modulation controller 156 (PMW), the first microprocessor 155 will be a certain frequency The triangular wave and a reference signal of a certain voltage are input to the first pulse width modulation controller 156, and the first pulse width modulation controller 156 uses the triangular wave of the certain frequency and the reference signal of a certain voltage to the first RF power generator 153. Turn on time and off time for control.

In this embodiment, the first microprocessor 155 stores a triangular wave of a certain frequency and a reference signal of a certain voltage, the frequency function of the triangular wave is f _o (t), and the voltage function of the reference signal is V. _Ref (t), the frequency function of the triangular wave and the voltage function of the reference signal change with time, and are a step function or a continuous function. The first microprocessor 155 inputs the triangular wave of a certain frequency and a reference signal of a certain voltage to the first pulse width modulation controller 156, and the first pulse width modulation controller 156 controls the first radio frequency according to the following formula. The turn-on time Ton(t) and the turn-off time _Toff (t) of the power generator 153, f _o (t)=1/(T _on (t)+T _off (t)), V _ref (t)=a× T _on (t) / T _off (t), where a is a specific coefficient. Therefore, the radio frequency signal generated by the first radio frequency power generator is a pulse signal, that is, a first pulse signal, and the frequency of the triangular wave corresponds to a pulse frequency of the first pulse signal output by the first radio frequency power generator. The voltage of the reference signal corresponds to the ratio of the on time of the first pulse signal to the off time. The pulse frequency and the pulse duty ratio of the first pulse signal output by the bias RF power source 150 can be controlled by the triangular wave having a certain frequency and the reference signal of a certain voltage stored in the first microprocessor 155. Since the frequency function of the triangular wave and the voltage function of the reference signal change with time, that is, the pulse frequency and the pulse duty ratio of the first pulse signal output by the bias RF power source 150 also change with time. .

In other embodiments, the first microprocessor has a data table that stores a frequency value of a time-dependent triangular wave and a voltage value of a reference signal, the first microprocessor corresponding to the corresponding time After reading the frequency value of the triangular wave and the voltage value of the corresponding reference signal, inputting the triangular wave of the corresponding frequency and the reference signal of the corresponding voltage to the first pulse width modulation controller, and controlling the first pulse width modulation controller The turn-on and turn-off times of an RF power generator to form a first pulse signal having a particular pulse frequency and pulse duty cycle.

The first pulse signal generated by the bias RF power source 150 is used to form a bias voltage on the surface of the substrate to be etched, and the surface of the substrate to be etched is biased when the first pulse signal is in an open state. The plasma in the reaction chamber is caused to cause the plasma to bombard the substrate to be etched, and an etching step is performed; when the first pulse signal is in a closed state, the surface of the substrate to be etched is not polarized. The pressure is such that the plasma forms a polymer on the sidewalls of the trench formed by etching to protect the sidewall from being overetched. And by controlling the reference letter stored in the first microprocessor 155 The function is such that the pulse duty cycle of the biased RF power source 150 can be controlled to control the amount of polymer of the trench sidewalls formed by etching at different depths, thereby controlling the slope of the trench sidewalls at different depths. When the first pulse signal is in a closed state for a long time, the number of polymers on the sidewall of the trench is larger, and the slope of the trench is larger; when the first pulse signal is in a closed state, the time is short, The number of polymers on the sidewalls of the trench is small and the slope of the trench is small. In one of the embodiments, as the etching depth increases, the number of formed polymers is gradually increased by increasing the time during which the first pulse signal is in a closed state, forming a trench with sidewalls inclined, so that the final formed The cross-section of the groove results in an inverted triangle or an inverted trapezoid, which facilitates the filling of subsequent materials. When the high aspect ratio via hole is etched, since the plasma does not easily enter the through hole, the step of the first etching step and the step of forming the polymer becomes longer by gradually reducing the frequency of the first pulse signal, thereby still being It can be etched at the same rate. Moreover, adjusting the pulse duty ratio and the pulse frequency of the first pulse signal can also adjust the average power of the bias RF power source 150 to affect the sheath characteristics and the plasma distribution.

Wherein, the etch rate can be controlled by independently increasing or decreasing the pulse frequency of the first pulse signal without changing the pulse duty ratio of the first pulse signal; without changing the pulse frequency of the first pulse signal Increasing or decreasing the pulse duty ratio of the first pulse signal alone can control the morphology of the etching structure; simultaneously changing the pulse duty ratio and the pulse frequency of the first pulse signal can control the shape and engraving of the etching structure Erosion rate.

Please refer to FIG. 3 , which is a schematic structural diagram of the plasma RF power source 140 of FIG. 1 . The plasma RF power source 140 specifically includes: a second RF power generator 143 and is connected to the second RF power generator 143 . a second RF signal generator 144, the second RF signal generator 144 includes a second microprocessor 145 and a second pulse width modulation controller 146, the second microprocessor 145 and a certain frequency of triangular waves The reference signal of the voltage is input to the second pulse width modulation controller 146, and the second pulse width modulation controller 146 utilizes the triangular wave of the certain frequency The reference signal of a certain voltage controls the on time and the off time of the second RF power generator 143.

In this embodiment, the second microprocessor 145 stores a triangular wave of a certain frequency and a reference signal of a certain voltage, the frequency function of the triangular wave is f _o (t), and the voltage function of the reference signal is V. _Ref (t), the frequency function of the triangular wave and the voltage function of the reference signal change with time, and are a step function or a continuous function. The second microprocessor 145 inputs the triangular wave of a certain frequency and a reference signal of a certain voltage to the second pulse width modulation controller 146, and the second pulse width modulation controller 146 (PMW) is controlled according to the following formula The turn-on time T _on (t) and the turn-off time T _off (t) of the second RF power generator 143, f _o (t) = 1 / (T _on (t) + T _off (t)), V _ref (t ) = a × T _on (t) / T _off (t), where a is a specific coefficient. Therefore, the radio frequency signal generated by the second RF power generator 143 is a pulse signal, that is, a second pulse signal, and the frequency of the triangular wave corresponds to the pulse frequency of the second pulse signal output by the second RF power generator 143. The voltage of the reference signal corresponds to a ratio of an on time to a off time of the second pulse signal. Therefore, the pulse frequency and the pulse duty ratio of the second pulse signal output by the plasma RF power source 140 can be controlled by the triangular wave having a certain frequency and the reference signal of a certain voltage stored in the second microprocessor 145. Since the frequency function of the triangular wave and the voltage function of the reference signal change with time, that is, the pulse frequency and the pulse duty ratio of the second pulse signal output by the plasma RF power source 140 also change with time. .

In other embodiments, the second microprocessor has a data table storing a frequency value of a time-dependent triangular wave and a voltage value of the reference signal, the second microprocessor corresponding to the corresponding time After reading the frequency value of the triangular wave and the voltage value of the corresponding reference signal, inputting the triangular wave of the corresponding frequency and the reference signal of the corresponding voltage to the second pulse width modulation controller, and controlling the second pulse width modulation controller The turn-on time and the turn-off time of the two RF power generators, thereby forming a second pulse signal having a specific pulse frequency and a pulse duty ratio.

a second pulse signal generated by the plasma RF power source 140 For plasmaizing a gas in the reaction chamber, the gas in the reaction chamber forms a plasma when the second pulse signal is in an open state; and when the second pulse signal is in a closed state, The gas in the reaction chamber does not continue to form a plasma. And by controlling the voltage function of the reference signal stored in the second microprocessor 145, controlling the pulse duty ratio of the plasma RF power source 140, the density and distribution of the plasma in the reaction chamber can be controlled, thereby controlling the etching rate. . And because the plasma RF power source 140 plasmaizes the gas, the formed plasma includes positive ions, negative ions, neutral radicals, and hot electrons, etc., wherein the hot electrons arrive at the near end due to small quality and high speed of movement. Etching the area of the surface of the substrate creates a negatively charged sheath near the surface of the substrate to be etched, which accelerates the positive ion bombardment of the substrate to be etched. When the second pulse signal is in the off state, since the lifetime of the hot electrons is short, the acceleration performance of the sheath layer is affected, and thus the pulse frequency of the plasma RF power source 140 is controlled, that is, by increasing or decreasing. The etching rate can also be controlled by the time when the second pulse signal is turned on and off.

Wherein, when the pulse frequency of the second pulse signal is separately increased or decreased without changing the pulse duty ratio of the second pulse signal, the etching rate can be controlled; when the pulse frequency of the second pulse signal is not changed In the case of increasing or decreasing the pulse duty ratio of the second pulse signal alone, the density and distribution of the plasma can be controlled; when the pulse duty ratio and the pulse frequency of the second pulse signal are simultaneously changed, the reaction chamber can be simultaneously controlled. Plasma density, distribution, and etch rate.

In this embodiment, the semiconductor etching apparatus further includes a control computer (not shown), the control computer is connected to the first microprocessor and the second microprocessor, and the control computer is to the first micro processing. And the second microprocessor inputs a frequency function of the triangular wave and a voltage function of the reference signal, thereby controlling a pulse frequency and a pulse duty ratio of the first pulse signal and the second pulse signal.

In other embodiments, the control computer inputs a frequency value of a time-dependent triangular wave and a voltage value of the reference signal to a data table of the first microprocessor and the second microprocessor, so that the first microprocessor and the second The microprocessor can correspond The frequency value and the voltage value control the pulse frequency of the first pulse signal and the second pulse signal and the pulse duty ratio.

In this embodiment, the semiconductor etching apparatus further includes an exhaust port (not shown) connected to a vacuum pump (not shown) for discharging reactants in the reaction chamber and excess The gas is discharged.

The embodiment of the invention further provides a semiconductor etching method using the above semiconductor etching device, which comprises: providing a substrate to be etched; introducing a reaction gas into the reaction chamber; and a plasma RF power source for the gas in the reaction chamber Plasmaizing; biasing the RF power source to apply a bias voltage on the surface of the substrate to be etched; etching the substrate to be etched by using the plasma of the gas to form an etched pattern, the plasma RF power source and the bias The RF signal output by the RF power source is a pulse signal. When the etched pattern has a first depth, the pulse signal has a first pulse duty ratio and a first pulse frequency. When the etched pattern has a second depth, the The pulse signal has a second pulse duty cycle and a second pulse frequency.

Referring to FIG. 1, the substrate to be etched 125 includes at least a semiconductor substrate, which is a germanium substrate, a germanium substrate, a germanium substrate, a tantalum nitride substrate, a germanium on insulator, and the like. The semiconductor substrate may be etched by the semiconductor etching method to form trenches or via holes. In other embodiments, the substrate to be etched includes a semiconductor substrate and one or more semiconductor layers or metal layers on the surface of the semiconductor substrate, and the semiconductor layer or the metal layer is further engraved by the semiconductor etching method. eclipse. In this embodiment, the substrate to be etched 125 is a single crystal germanium substrate.

The gas is introduced into the reaction chamber 110 through the gas supply source 130. In the embodiment, when the material to be etched is a single crystal crucible, the gas includes SF ₆ , C ₄ F ₈ , He, N _{2 .} One or several of them. In other embodiments, when the material to be etched is tantalum oxide or tantalum nitride, the gas includes CF ₄ , C ₄ F ₈ , C ₄ F ₆ , CH ₂ F ₂ , CHF ₃ , He, N _{2 .} One or several of them.

In this embodiment, the RF signal output by the plasma RF power source and the bias RF power source are pulse signals, and the pulse signal changes with time. In other embodiments, the RF signal outputted by the plasma RF power source or the bias RF power source is a pulse signal, and the pulse frequency and the pulse duty ratio of the pulse signal change with time. The other output RF signal is a pulse signal with a constant pulse frequency and pulse duty cycle or a continuous RF signal.

In this embodiment, the etched pattern has a first depth and a second depth. At a first depth, the bias RF power source outputs a first pulse signal, and the plasma RF power source outputs a second pulse signal, the first pulse signal and the second pulse signal having a first pulse frequency and a first Pulse duty cycle. At a second depth, the bias RF power source outputs a first pulse signal, the plasma RF power source outputs a second pulse signal, the first pulse signal and the second pulse signal having a second pulse frequency and a second Pulse duty cycle. The first pulse frequency and the second pulse frequency are different, and the first pulse duty ratio and the second pulse duty ratio are different, thereby adjusting sidewall morphology and etching rate of the etched pattern at different depths.

Referring to FIG. 2, in the embodiment, the specific method for controlling the first pulse signal output by the bias RF power source includes: inputting a triangular wave of a certain frequency and a reference signal of a certain voltage to the first by using a control computer. In the microprocessor 155, the triangular wave and the reference signal are piecewise functions and correspond to the first depth and the second depth, and the first microprocessor 155 inputs the triangular wave and the reference signal to the first pulse width modulation control. The first pulse width modulation controller 156 controls the turn-on time and the turn-off time of the first RF power generator 153 by using the triangular wave and the reference signal, so that the bias RF power source outputs the first pulse signal, wherein The frequency of the triangular wave corresponds to a pulse frequency of the first pulse signal, and the voltage of the reference signal corresponds to a ratio of an on time of the first pulse signal to a turn-off time, such that when the etched pattern has a first depth, The first pulse signal has a first pulse duty ratio and a first pulse frequency, and when the etched pattern has a second depth, the first The pulse signal has a second pulse duty cycle and a second pulse frequency.

Referring to FIG. 3, in the embodiment, the specific method for controlling the second pulse signal output by the plasma RF power source includes: inputting a triangular wave of a certain frequency and a reference signal of a certain voltage into the second by using a control computer. In the microprocessor 145, the triangular wave and the reference signal are piecewise functions and correspond to the first depth and the second depth, and the second microprocessor 145 inputs the triangular wave and the reference signal to the second pulse width modulation control. The second pulse width modulation controller 146 controls the turn-on time and the turn-off time of the second RF power generator 143 by using the triangular wave and the reference signal, so that the plasma RF power source outputs the second pulse signal, wherein The frequency of the triangular wave corresponds to a pulse frequency of the second pulse signal, and the voltage of the reference signal corresponds to a ratio of an on time of the second pulse signal to a turn-off time, such that when the etched pattern has a first depth, The second pulse signal has a first pulse duty ratio and a first pulse frequency, and the second pulse signal when the etched pattern has a second depth The number has a second pulse duty cycle and a second pulse frequency.

In this embodiment, the pulse duty ratio and the pulse frequency of the second pulse signal and the second pulse signal are equal and synchronously changed, that is, the plasma RF power source and the bias RF power source are simultaneously turned on and simultaneously turned off. In other embodiments, the pulse duty ratio and the pulse frequency of the second pulse signal and the second pulse signal may be equal but not synchronously changed, and have a certain phase difference. In other embodiments, the pulse duty ratio and the pulse frequency of the second pulse signal and the second pulse signal may also be unequal, and the two are independent of each other.

In other embodiments, the pulse frequency or pulse duty ratio of the first pulse signal and the second pulse signal may be separately adjusted at different depths, thereby adjusting sidewall morphology and etching rate of the etched pattern at different depths.

In one embodiment, the frequency of the triangular wave remains unchanged, and the voltage of the reference signal changes with time, so that the pulse frequency of the pulse signal output by the biased RF power source and the plasma RF power source is constant. In the case, the ratio between the on time and the off time of the pulse signal is changed.

In another embodiment, the frequency of the triangular wave changes with time, and the voltage of the reference signal remains unchanged, such that the biased RF power source, the first pulse signal output by the plasma RF power source, and the first pulse are When the ratio between the signal on time and the off time remains unchanged, changing the pulse frequency of the first pulse signal and the first pulse signal, thereby changing the bias RF power source and the plasma RF power source to be turned on and off. time.

In another embodiment, when the biased RF power source, the first pulse signal output by the plasma RF power source, the first pulse signal turn-on time or the turn-off time are unchanged, the corresponding turn-off time or turn-on time is changed. The first pulse signal, the pulse frequency of the first pulse signal, and the pulse duty ratio are changed.

In other embodiments, the etched pattern may have at least three different depth segments, and the pulse frequency and/or the pulse duty ratio of the first pulse signal and the second pulse signal corresponding to different depth segments are different, thereby Adjust the sidewall morphology and etch rate of the etched pattern at different depths.

In this embodiment, the pulse frequency of the second pulse signal and the second pulse signal is less than 50 kHz, and the pulse duty ratio of the second pulse signal and the second pulse signal is 10% to 90%.

The present invention has been disclosed in the above preferred embodiments, but it is not intended to limit the present invention. Any one skilled in the art can use the above disclosed methods and technical contents to the present invention without departing from the spirit and scope of the present invention. The technical solution makes possible changes and modifications, and the above techniques are applied to plasma deposition, plasma surface treatment, etc., and therefore, any of the above embodiments can be made according to the technical essence of the present invention without departing from the technical solution of the present invention. Simple modifications, equivalent changes, and modifications are all within the scope of protection of the present invention.

110‧‧‧Reaction chamber

120‧‧‧Sheet

125‧‧‧ substrates to be etched

130‧‧‧ gas supply

140‧‧‧ Plasma RF power source

141‧‧‧Second RF Matcher

142‧‧‧Inductance coil

150‧‧‧Bad RF power source

151‧‧‧First RF Matcher

Claims (13)

A semiconductor etching apparatus includes: a reaction chamber having a wafer stage for placing a substrate to be etched; a gas supply source for introducing gas into the reaction chamber; and a plasma RF power source, For plasmaizing the gas in the reaction chamber; biasing a radio frequency power source for forming a bias voltage on the surface of the substrate to be etched; and outputting the plasma RF power source and/or the bias RF power source The RF signal is a pulse signal, and the pulse frequency and the pulse duty ratio of the pulse signal change with time; wherein the bias RF power source includes a first RF power generator and is coupled to the first RF power generator Connected to a first RF signal generator, the first RF signal generator comprising a first microprocessor and a first pulse width modulation controller, the first microprocessor to reference a triangular wave of a specific frequency and a specific voltage Transmitting a signal to the first pulse width modulation controller, the first pulse width modulation controller utilizing the triangular wave of the specific frequency and the reference signal of the specific voltage to open the first RF power generator The start time and the off time are controlled, wherein the frequency of the triangular wave corresponds to a pulse frequency of the first pulse signal output by the first RF power generator, and the voltage of the reference signal corresponds to an on time and a turnoff of the first pulse signal The ratio of time. The semiconductor etching apparatus of claim 1, wherein the plasma RF power source comprises a second RF power generator and a second RF signal generator connected to the second RF power generator, the second RF signal The generator includes a second microprocessor and a second pulse width modulation controller, the second microprocessor inputs a triangular wave of a certain frequency and a reference signal of a certain voltage to the second pulse width modulation controller, the second pulse width The modulation controller controls the turn-on time and the turn-off time of the second RF power generator by using the triangular wave of the certain frequency and the reference signal of the certain voltage, wherein the frequency of the triangular wave corresponds to the output of the second RF power generator The pulse frequency of the second pulse signal, the voltage of the reference signal corresponding to the ratio of the on time of the second pulse signal to the off time. The semiconductor etching apparatus of claim 2, wherein the first pulse width modulation controller and the second pulse width modulation controller respectively control the first RF power generator and the second RF power generator according to the following formula Opening time T _on (t) and closing time T _off (t), f _o (t)=1/(T _on (t)+T _off (t)), V _ref (t)=a×T _on ( t) / T _off (t), where f _o (t) is a function of the frequency of the triangular wave, V _ref (t) is a function of the voltage of the reference signal, and a is a specific coefficient. The semiconductor etching apparatus of claim 3, wherein the frequency of the triangular wave and the voltage of the reference signal change with time. The semiconductor etching apparatus of claim 3, wherein the first microprocessor calculates a frequency of a triangular wave corresponding to a certain time and a voltage of a reference signal according to a frequency function of the triangular wave and a voltage function of the reference signal, and And inputting, by the second microwave, a triangular wave corresponding to the time-frequency corresponding to The frequency and the voltage of the reference signal, and input the triangular wave of the corresponding frequency and the reference signal of the corresponding voltage to the second pulse width modulation controller. The semiconductor etching apparatus of claim 3, wherein the first microprocessor and the second microprocessor store a frequency value of a time-dependent triangular wave and a voltage value of a reference signal, the first microprocessor, The second microprocessor reads the frequency value of the triangular wave corresponding to the corresponding time and the voltage value of the corresponding reference signal, and then inputs the triangular wave of the corresponding frequency and the reference signal of the corresponding voltage to the first pulse width modulation control The second pulse width modulation controller. The semiconductor etching apparatus of claim 2, further comprising a control computer, wherein the control computer is used to input a frequency function of the triangular wave, a voltage function of the reference signal to the first microprocessor and the second microprocessor, or The first microprocessor and the second microprocessor input a frequency value of a time-dependent triangular wave and a reference signal Pressure value. The semiconductor etching apparatus of claim 1, further comprising: the bias RF power source connected to the stage via a first RF matcher. The semiconductor etching apparatus of claim 1, further comprising: the bias RF power source connected to the top of the reaction chamber by a first RF matcher. The semiconductor etching apparatus of claim 1, wherein the plasma RF power source is an inductively coupled RF power source or a capacitively coupled RF power source. A semiconductor etching method using the semiconductor etching apparatus according to claim 1, comprising: providing a substrate to be etched; introducing a gas into the reaction chamber; and a plasma RF power source for the gas plasma in the reaction chamber Applying a bias voltage to the surface of the substrate to be etched by using a biased RF power source; etching the substrate to be etched by using a plasma of the gas to form an etched pattern, the plasma RF power source and/or bias The signal output from the RF signal output by the RF power source is a pulse signal. When the etched pattern has a first depth, the pulse signal has a first pulse duty ratio and a first pulse frequency, and the etched pattern has a second At depth, the pulse signal has a second pulse duty cycle and a second pulse frequency. The semiconductor etching method according to claim 11, wherein the pulse signal has a pulse frequency of less than 50 kHz, and the pulse signal has a pulse duty ratio ranging from 10% to 90%. The semiconductor etching method of claim 11, wherein the etched pattern further comprises at least a third depth, the pulse frequency and/or the pulse duty ratio of the first pulse signal and the second pulse signal corresponding to the third depth The first depth and the second depth are different, thereby adjusting sidewall morphology and etching rate of the etched pattern at different depths.