KR100801857B1 - Method for ashing substrates - Google Patents

Abstract

A method for ashing a substrate is provided to improve productivity and to reduce generation of particles by rapidly removing polymers without damage. A substrate(W) is separated from a heating plate(120). A process gas is supplied to a space between a rear surface of the substrate and the heating plate. Bias power is applied to the heating plate in order to form a plasma state of the process gas in the space between the rear surface of the substrate and the heating plate. The process gas includes at least one additional gas and an oxygen gas selected from a fluorine-based etching gas. The additional gas corresponds to 0.1 to 10 percent of the total weight of the process gas.

Description

Substrate Ashing Method {METHOD FOR ASHING SUBSTRATES}

1 is a schematic configuration diagram of an ashing apparatus for an ashing process according to the present invention.

2 is a view illustrating a substrate front ashing process in a lift pin down state.

3 is a view showing a substrate backing process in the lift pin up state.

4-6 are flowcharts for various ashing processes of the present invention.

<Description of Symbols for Major Parts of Drawings>

110: process chamber

120: heating plate

130: lift assembly

140: lower electrode

160: plasma source unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing process, and more particularly, to an ashing method for removing foreign matter (polymer) on a substrate backside (back side) and a photoresist on the front surface of a substrate generated during an etching process.

Foreign material generated during the dry etching process is generated on the front surface of the substrate, but is also formed at the rear edge. In dry photoresist strips, it is difficult or difficult to remove the backing, so that the foreign material has been removed in a wet cleaning process.

Attempts in traditional dry photoresist strips have introduced the technique of removing the front and back simultaneously using a pin up process or using an edge cut hot plate, but due to the limitations of the wet strip ( wet strip).

In order to remove the polymer on the back surface of the substrate, a long process time is required at high temperature, or an etching gas (CF4) is required at low temperature.

High temperature long process times increase the damage of substrate front elements, which is fatal to yield. In particular, it is a process that is not applicable in a low-k process or a copper metal process. The application of the etching gas also exposes the front surface of the substrate to the plasma during the time of removing the foreign substances on the back surface of the substrate, and thus the etching of the undesired layer is impossible.

An object of the present invention is to provide an ashing method that can remove foreign substances (polymer by-product by etching) on the back surface of the substrate in a photoresist removal process without any additional process.

It is an object of the present invention to provide an ashing method that can remove foreign substances on the back side of a substrate in a short process time without damaging the layer film on the front side of the substrate.

According to a feature of the present invention for achieving the above object, the substrate ashing method is applied to the heating plate while supplying a processing gas to the space between the substrate and the heating plate while the substrate is spaced from the heating plate at the same time In this way, the processing gas in the space between the substrate and the heating plate is converted into plasma to remove the polymer at the back of the substrate.

According to an embodiment of the present invention, the process gas includes at least one additive gas selected from a fluorine series etching gas and an oxygen (02) gas.

According to an embodiment of the invention, the additive gas is from 0.1% to 10% of the total weight of the process gas.

According to the exemplary embodiment of the present invention, when the fluorine-based etching gas is added to the processing gas, the upper plasma source positioned on the upper part of the substrate is protected while the power is cut off.

According to an exemplary embodiment of the present invention, the substrate ashing method may apply bias power to the heating plate while the substrate is placed on the heating plate, and apply microwave power to an upper plasma source positioned above the substrate to provide a substrate upper space. Plasma treatment of the process gas to remove the photoresist and polymer on the front surface of the substrate, wherein removing the photoresist and polymer on the front surface of the substrate is performed before or after the polymer removal step on the back of the substrate. .

According to an exemplary embodiment of the present invention, microwave power is applied to an upper plasma source positioned above the substrate to convert the processing gas in the upper space of the substrate into plasma to remove photoresist and polymer on the front surface of the substrate simultaneously with removing the polymer on the back of the substrate. do.

According to an embodiment of the present invention, in order to simultaneously remove the photoresist and polymer on the front and rear surfaces of the substrate, at least one gas and oxygen selected from the group of additive gases consisting of nitrogen gas, inert gas, and reducing gas-based gas may be used. It is made of gas, and a strong bias power of 400-600W is applied to the lower electrode of the heating plate.

According to an embodiment of the present invention, the process gas is nitrogen (N2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H2) gas, helium hydrogen (H2He) gas, nitrogen hydrogen (H2N2) gas At least one gas selected and oxygen (O 2) gas.

According to an embodiment of the present invention, the height at which the substrate is spaced apart from the heating plate is adjusted according to the thickness of the sheath formed on the heating plate by the bias power.

According to an embodiment of the invention, the height of the substrate spaced from the heating plate is adjusted by lift pins.

In accordance with an embodiment of the present invention, the substrate is maintained at a low temperature of 20-80 degrees.

According to another aspect of the present invention, a substrate ashing method in a system using an upper plasma source and a lower electrode bias power may include depressurizing the inside of a process chamber and heating the substrate to a low temperature (20-80 degrees) at room temperature; The lower electrode bias power is applied while the substrate is placed on the heating plate, and the microwave power is applied to the upper plasma source positioned above the substrate to convert the first processing gas supplied to the upper space of the substrate into a plasma to form a front surface of the substrate. Removing the photoresist and the polymer; The microwave power applied to the upper plasma source is cut off, and a bias power is applied to the lower electrode of the heating plate positioned below the substrate while the substrate is spaced apart from the heating plate to supply the space between the substrate and the heating plate. Plasmalizing the second processing gas to remove the polymer on the back surface of the substrate.

According to an embodiment of the present invention, the second processing gas includes at least one additive gas selected from a fluorine series etching gas and an oxygen (02) gas.

According to an embodiment of the present invention, the first processing gas is nitrogen (N 2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H 2) gas, helium hydrogen (H 2 He) gas, nitrogen hydrogen (H 2 N 2) It includes at least one gas selected from the gas and oxygen (O2) gas.

According to an embodiment of the present invention, the height at which the substrate is spaced apart from the heating plate is adjusted according to the thickness of the sheath formed on the heating plate by the bias power.

According to the exemplary embodiment of the present invention, the polymer removing step of the rear surface of the substrate is performed while the substrate is spaced 1-2 cm from the heating plate.

Hereinafter, an ashing method according to the present invention will be described in detail with reference to the accompanying drawings.

The invention is not limited to the embodiments described herein but may be embodied in other forms. The embodiments introduced herein are provided to make the disclosed contents thorough and complete, and to fully convey the spirit and features of the present invention to those skilled in the art. In the drawings, each device is schematically shown for clarity of the invention. Each device may also be equipped with a variety of additional devices not described in detail herein. Like reference numerals denote like elements throughout the specification.

(Example)

1 is a view schematically showing an ashing apparatus using a plasma.

Referring to FIG. 1, the ashing apparatus 100 of the present invention is a device for removing photoresist remaining after dry etching or after an ion implantation process using plasma, and by-products of the front and back surfaces of the substrate generated during dry etching (polymer ) Removal is a device that can be removed simultaneously in the ashing process without any additional process.

The ashing apparatus 100 of the present invention includes a process chamber 110 that provides a predetermined closed atmosphere.

In the upper portion of the process chamber 110, a plasma source unit 160 to which microwave power for generating plasma is supplied, and a gas supply unit 180 to selectively supply the first processing gas and the second processing gas are positioned. . The plasma source unit 160 supplies microwave power to the plasma tube 162, the microwave waveguide 164 and the microwave waveguide 164 surrounding the plasma tube 162 so as to be orthogonal to the plasma tube 162. And a microwave generator 166. The first processing gas is introduced into the plasma tube 162 through the upper supply port 162a of the plasma tube 162, and the first processing gas is induced by ionizing the microwaves generated in the microwave waveguide 164 to induce plasma The plasma is generated in the tube 162.

The gas supply unit 180 selectively supplies the first processing gas and the second processing gas. The first treatment gas includes at least one participating gas selected from nitrogen (N2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H2) gas, helium hydrogen (H2He) gas, and nitrogen hydrogen (H2N2) gas. (O2) gas. The second processing gas includes at least one additive gas selected from a fluorine series etching gas and an oxygen (02) gas. The first process gas is used to remove the photoresist and polymer on the front of the substrate, and the second process gas is used to remove the polymer on the back of the substrate. In general, since the polymer attached to the back of the substrate is difficult to remove with a conventional ashing gas and takes a long time, in the present invention, the polymer on the back of the substrate is used by using a second process gas containing a fluorine-based etching gas. Can be removed quickly.

The plasma generated by the plasma source unit 160 is provided to the process chamber 110 through a gas distribution plate (GDP) 118 installed to face the substrate w. The gas distribution plate 118 has a plurality of injection holes 119 formed at regular intervals on the concentric circumference for uniform gas supply.

In the process chamber 110, a heating plate 120 is provided on which a substrate w, which is placed at an input position by a robot, is disposed as the gate door 111 is opened.

The heating plate 120 may include a heater for heating the substrate to a predetermined temperature, a lift assembly 130 and a lower electrode 140 driven up and down in a form of supporting the substrate to facilitate the transfer of the substrate by the robot described above. It has a conventional configuration provided.

The heating plate 120 is maintained at an appropriate temperature (range of 20-80 degrees) at which the photoresist and polymer on the substrate w can be removed. Preferably, the substrate is preferably maintained at room temperature of 25 degrees to prevent damage to the semiconductor device. The lift assembly 130 includes lift pins 132 and lift pins 132 that support and support the bottom surface of the substrate w, which is placed by the robot (not shown) according to the opening of the gate door 111. And a driver 134 for raising (up position) / lowering (down position). In order to remove foreign substances on the rear surface of the substrate, the substrate w is heated by the lift pins 132 from the upper surface of the heating plate 120 (the position shown in FIG. 3) and the heating for removing the photoresist on the upper surface of the substrate. The plate 120 is moved to a down position (position shown in FIG. 2) on the upper surface.

The lower electrode 140 is connected to the bias power unit 142. A bias power of 500 W is applied to the lower electrode 140 to remove the polymer on the back surface of the substrate by plasmalizing the processing gas in the space between the substrate w and the heating plate 120.

A vacuum suction port 116 is formed at the bottom of the process chamber 110 to be connected to the vacuum pump. The vacuum exhaust unit 150 is for forming the inside of the process chamber 110 in a vacuum state and for discharging reaction by-products generated during the ashing process, and the pump 152 and the vacuum port 116. It includes a vacuum line 154 connected. Various valves (not shown) are installed in the vacuum line 154 connecting the process chamber 110 and the pump 152 to control the degree of vacuum by opening and closing the vacuum line 154 and adjusting the opening and closing degree.

4 is a flowchart of an ashing process according to a preferred embodiment of the present invention.

An ashing process in the above-described ashing apparatus will be described in detail with reference to FIGS. 2 to 4.

As shown in Figures 2 to 4, the ashing process according to the present invention is a process for removing the photoresist and the polymer on the bottom surface of the substrate used in the etching process or ion implantation process, the present invention effectively It is characterized by having a substrate back side ashing step s130 after the substrate front side ashing step s120 for removal.

The ashing process according to an embodiment of the present invention includes the step (s110) of loading the substrate (w) on which the photoresist and polymer to be removed is formed into the inside of the process chamber (in detail, the upper portion of the heating plate) (s110). do.

Transfer of the substrate in the step (s110) is made by a robot (or handler) installed outside the process chamber 110. For reference, as soon as the process starts, the heating plate 120 may maintain its temperature until the process is completed at 25 or the temperature may be adjusted according to each step. When the substrate w is transferred into the process chamber 110, the lift pins 132 support the substrate w while being lifted from the heating plate 120 by operating a pin driver. When the substrate is supported by the lift pins 132, the robot is returned to the outside of the process chamber 110, and as the lift pins 132 are lowered, the substrate is placed on the heating plate.

By operating the vacuum pump 152 in a state where the process chamber 110 is sealed, the process chamber 110 is made into a vacuum state of 100-1000 mT (s130). While the process chamber 110 is converted from the normal pressure to the vacuum state, the substrate w is maintained at a temperature of about 25 degrees while being placed on the heating plate 120.

When the process chamber 110 is decompressed to a vacuum state and the substrate is heated, the substrate front ashing process s120 is performed. 2 is a view illustrating a substrate front ashing process in a state in which the lift pin 132 is down. As illustrated in FIG. 2, the substrate front ashing process s120 is performed by plasma using microwave power and plasma by bias power. Depending on the ashing target, only microwaves may be used, but bias power may be used simultaneously. The use of bias power together results in higher ashing rates and is required for copper (Cu) products that require low temperature ashing. The substrate front ashing process includes at least one participating gas selected from nitrogen (N2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H2) gas, helium hydrogen (H2He) gas, and nitrogen hydrogen (H2N2) gas. The first processing gas containing the (O2) gas is used.

Here, the microwave power of the plasma source unit 160 is 2500W, the bias power of the lower electrode 140 is 500W, the pressure in the process chamber 110 is 1000mT, the process temperature of the substrate is 250 ??, the lift pin 132 It is desirable to proceed for 30 seconds in the down state.

When the front ashing process of the substrate is completed, the back ashing process of the substrate is performed. 3 is a view showing a substrate backing process in the lift pin up state.

As shown in FIG. 3, the substrate back ashing process s130 is performed in order to quickly remove polymer on the back surface of the substrate generated during the dry etching process, using a fluorine series (carbon tetrafluoride (CF4) and trifluoromethane (CHF3)). Etc.) and a second processing gas including one additive gas selected from an etching gas and an oxygen (02) gas. The additive gas contains 0.1% -10% of the total gas weight. Note that in the substrate backing process, the microwave power must be turned off and the substrate w must be 1-2 cm away from the heating plate 120 to protect the front surface of the substrate. The bias power provided is that the power must be provided at 500W.

When the substrate rear ashing is applied with the bias power to the lower electrode 140 while the substrate is spaced apart from the heating plate 120, the second processing gas in the space between the substrate w and the heating plate 120 is converted into plasma. This will remove the polymer from the back of the substrate. For example, a sheath of several mm intervals is formed between the lower electrode 140 and the substrate due to the bias power. The substrate may be removed from the heating plate 120 because it affects the entire surface of the substrate w according to this value. The spaced height can vary depending on the sheath thickness. When the substrate back ashing process is performed under the following conditions, it is preferable to be spaced apart by 1.5cm height.

For example, the microwave power of the plasma source 160 is 0W, the bias power of the lower electrode 140 is 500W, the pressure of the process chamber 110 is 1000mT, the process temperature of the substrate is 250 ?? It is preferred to proceed for 30 seconds in the up state.

As shown in FIG. 4, the substrate front ashing s120 and the substrate rear ashing s130 may each proceed in separate steps, and as shown in FIG. 5, the substrate rear ashing s130 may be a substrate front ashing s120. You may proceed earlier.

As shown in FIG. 6, when there is no influence on the entire surface of the substrate (that is, when the bias power is very low (less than 500W, and no fluorine-based etching gas is used), the plasma with the microwave power as the source in the lift pin up state and At the same time, the front and rear surfaces of the substrate may be simultaneously processed using plasma by bias power (S150).

When the back ashing process (s130) of the substrate is completed, power and gas supply are stopped, the process chamber 110 is pumped into a vacuum to purify the inside of the chamber, and nitrogen gas is supplied again to atmospheric pressure inside the process chamber 110. After forming, the ashing process is completed by unloading the substrate (s140).

The foregoing detailed description illustrates the present invention. In addition, the foregoing description merely shows and describes preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. And, it is possible to change or modify within the scope of the concept of the invention disclosed in this specification, the scope equivalent to the written description, and / or the skill or knowledge in the art. The above-described embodiments are for explaining the best state in carrying out the present invention, the use of other inventions such as the present invention in other state known in the art, and the specific fields of application and uses of the present invention. Various changes are also possible. Accordingly, the detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Also, the appended claims should be construed to include other embodiments.

As described in detail above, the present invention can quickly remove the intrinsic polymer on the back side of the substrate without damaging the front side. In addition, the present invention can remove the polymer on the back of the substrate without a separate process step or device. In addition, the present invention can replace the wet cleaning process, there is a cost reduction effect. In addition, the present invention has the effect of improving yield and reducing particle generation.

Claims (16)

In the substrate ashing method: While the substrate is spaced apart from the heating plate, the processing gas is supplied to the space between the rear surface of the substrate and the heating plate, and a bias power is applied to the heating plate to plasma-process the processing gas in the space between the rear surface of the substrate and the heating plate. A substrate ashing method comprising removing the polymer on the back side. The method of claim 1, And said processing gas comprises at least one additive gas selected from a fluorine series etching gas and an oxygen gas. The method of claim 2, Wherein said additive gas is from 0.1% to 10% of the total weight of said processing gas. The method of claim 2, And when the fluorine-based etching gas is added to the processing gas, the upper plasma source positioned above the substrate to protect the entire surface of the substrate while the power is cut off. The method of claim 1, The substrate ashing method When the substrate is placed on the heating plate, bias power is applied to the heating plate, and microwave power is applied to the upper plasma source positioned above the substrate to plasma-process the processing gas in the upper space of the substrate to form a photoresist on the front surface of the substrate. Removing the polymer further; Removing the photoresist and polymer on the front surface of the substrate before or after removing the polymer on the back surface of the substrate. The method of claim 1, A substrate ashing method comprising applying microwave power to an upper plasma source positioned above a substrate to plasmaate the processing gas in the upper space of the substrate to simultaneously remove the photoresist and polymer on the front surface of the substrate and remove the polymer on the back surface of the substrate. . The method of claim 6, In order to simultaneously remove the photoresist and the polymer on the front and rear surfaces of the substrate, the processing gas is composed of at least one gas and an oxygen gas selected from an additional gas group consisting of nitrogen gas, inert gas, and reducing gas-based gas. Substrate ashing method characterized in that a bias power of 400-600W is applied to the lower electrode of the plate. The method of claim 1, The treatment gas includes at least one selected from nitrogen (N 2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H 2) gas, helium hydrogen (H 2 He) gas, and nitrogen hydrogen (H 2 N 2) gas and oxygen (O 2). A substrate ashing method comprising a gas. The method of claim 1, And a height at which the substrate is spaced apart from the heating plate is adjusted according to the thickness of the sheath formed on the heating plate by bias power. The method of claim 1, The height of the substrate spaced from the heating plate is controlled by the lift pins. The method of claim 1, Substrate ashing method, characterized in that the substrate is maintained at a temperature of 20-80 degrees. A substrate ashing method in a system using an upper plasma source and a lower electrode bias power: Reducing the interior of the process chamber and heating the substrate; While the substrate is placed on the heating plate, microwave power is applied to the upper plasma source positioned above the substrate, and bias power is applied to the lower electrode of the heating plate to supply the first processing gas supplied to the upper space of the substrate. Plasma forming to remove the photoresist and polymer on the front surface of the substrate; The microwave power applied to the upper plasma source is cut off, and a bias power is applied to the lower electrode of the heating plate positioned below the substrate while the substrate is spaced apart from the heating plate to supply the space between the substrate and the heating plate. Plasmalizing the second processing gas to remove the polymer on the back surface of the substrate. The method of claim 12, And said second processing gas comprises at least one additive gas selected from a fluorine series etching gas and an oxygen gas. The method of claim 12, The first processing gas includes at least one gas selected from nitrogen (N 2) gas, helium (He) gas, argon (Ar) gas, hydrogen (H 2) gas, helium hydrogen (H 2 He) gas, and nitrogen hydrogen (H 2 N 2) gas and oxygen. (O2) A substrate ashing method comprising a gas. The method of claim 12, And a height at which the substrate is spaced apart from the heating plate is adjusted according to the thickness of the sheath formed on the heating plate by bias power. The method of claim 12, And removing the polymer from the rear surface of the substrate, wherein the substrate is separated from the heating plate by 1-2 cm.

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