JP6516603B2 - Etching method and etching apparatus - Google Patents

Description

  The present invention relates to an etching method and an etching apparatus.

Etching that etches a layer to be etched containing polycrystalline silicon by supplying hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen (O ₂ ) gas and plasma generated from these gases A method has been proposed (see, for example, Patent Document 1).

JP, 2013-258244, A

  However, when forming a hole in a silicon film by etching, if the aspect ratio is increased to, for example, 15 or more, a phenomenon in which the tip of the etched hole is deflected (hereinafter referred to as "Twisting") occurs. The etched shape becomes worse. In recent years, the need for device refinement and high aspect ratio etching in particular has made the task of twisting more and more apparent.

  With respect to the above-mentioned subject, in one side, the present invention aims to make etching shape good.

According to one aspect of the present invention, there is provided an etching method for etching a silicon film formed on a substrate, comprising: hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas, and The method includes a plurality of steps of supplying a gas containing oxygen (O ₂ ) gas into the chamber and etching the silicon film by plasma generated from the supplied gas, wherein the flow rate of the hydrogen bromide gas is An etching method is provided in which the flow rate of the oxygen gas is gradually decreased and the flow rate of the oxygen gas is adjusted according to the decrease of the hydrogen bromide gas.

  According to one aspect, the etching shape can be improved.

The figure which shows the longitudinal cross-section of the etching apparatus concerning one Embodiment. The figure for demonstrating twisting to an ideal etching. The time chart which shows supply of gas at the time of etching in one embodiment and a comparative example. The figure which shows the relationship of the aspect ratio and twisting in one Embodiment and a comparative example. The figure which shows the etching shape in one embodiment and a comparative example. FIG. 2 is a view showing an example of an etching method according to an embodiment. The figure which shows an example of the relationship between the bottom CD value of LF concerning a modification of one embodiment, and a twisting value. The figure which shows an example of the twisting value concerning the modification of one Embodiment. The figure which shows an example of the effect of the etching method concerning the modification of one Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and the drawings, substantially the same configuration is given the same reference numeral to omit redundant description.

[Overall configuration of etching apparatus]
First, an example of an etching apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1: shows an example of the longitudinal cross-section of the etching apparatus 1 concerning this embodiment. The etching apparatus 1 according to the present embodiment is a parallel plate type plasma processing apparatus (capacitively coupled plasma processing apparatus) in which the mounting table 20 and the gas shower head 25 are disposed opposite to each other in the chamber 10. The mounting table 20 has a function of holding a substrate to be processed (hereinafter, simply referred to as “wafer W”) such as a semiconductor wafer and functions as a lower electrode. The gas shower head 25 has a function of supplying a gas into the chamber 10 in a shower shape and functions as an upper electrode.

  The chamber 10 is, for example, cylindrical and made of aluminum whose surface is anodized (anodized). The chamber 10 is electrically grounded. The mounting table 20 is installed at the bottom of the chamber 10 and mounts the wafer W thereon. The wafer W is an example of a substrate to be etched, and on the wafer W, a mask is formed on a polysilicon film.

The mounting table 20 forms a support 104 made of, for example, aluminum (Al), titanium (Ti), silicon carbide (SiC) or the like, and the upper surface of the mounting table 20, and is used for electrostatically attracting the wafer. An electric chuck 106 is provided. The electrostatic chuck 106 has a structure in which a chuck electrode 106 a is sandwiched between insulators 106 b made of a dielectric such as alumina (Al ₂ O ₃ ), for example.

  A direct current voltage source 112 is connected to the chuck electrode 106a, and a direct current is supplied from the direct current voltage source 112 to the chuck electrode 106a. Thereby, the wafer W is attracted to the surface of the electrostatic chuck 106 by the coulomb force.

  A refrigerant channel 104 a is formed in the support 104. A refrigerant inlet pipe 104b and a refrigerant outlet pipe 104c are connected to the refrigerant channel 104a. A cooling medium such as cooling water or brine output from the chiller 107 circulates through the refrigerant inlet pipe 104b, the refrigerant flow path 104a, and the refrigerant outlet pipe 104c. Thus, the mounting table 20 and the electrostatic chuck 106 are cooled.

  The heat transfer gas supply source 85 supplies a heat transfer gas such as helium gas (He) or argon gas (Ar) to the back surface of the wafer W on the electrostatic chuck 106 through the gas supply line 130. With this configuration, the temperature of the electrostatic chuck 106 is controlled by the cooling medium circulated in the coolant channel 104 a and the heat transfer gas supplied to the back surface of the wafer W. As a result, the wafer can be controlled to a predetermined temperature. Alternatively, the wafer W may be heated by using a heat source.

  The mounting table 20 is connected to a power supply device 30 that supplies two-frequency superimposed power. The power supply device 30 includes a first high frequency power supply 32 for supplying high frequency power HF for generating plasma at a first frequency, and a high frequency power LF for low frequency bias for a second frequency lower than the first frequency. And a second high frequency power supply 34 for supplying the The first high frequency power supply 32 is electrically connected to the mounting table 20 via the first matching unit 33. The second high frequency power supply 34 is electrically connected to the mounting table 20 via the second matching unit 35. The first high frequency power supply 32 applies, for example, high frequency power HF for plasma excitation of 100 MHz to the mounting table 20. The second high frequency power supply 34 applies a high frequency power LF for bias of 13.56 MHz to the mounting table 20, for example. In the present embodiment, the high frequency power HF is applied to the mounting table 20, but may be applied to the gas shower head 25.

  The first matching unit 33 matches the load impedance to the internal (or output) impedance of the first high frequency power supply 32. The second matching unit 35 matches the load impedance to the internal (or output) impedance of the second high frequency power supply 34. The first matching unit 33 functions so that the internal impedance of the first high frequency power supply 32 and the load impedance seem to match when the plasma is generated in the chamber 10. The second matching device 35 functions so that the internal impedance of the second high frequency power supply 34 and the load impedance apparently match when plasma is generated in the chamber 10.

  The gas shower head 25 is attached so as to close the opening of the ceiling portion of the chamber 10 via an insulating member which insulates the peripheral portion. The gas shower head 25 may be electrically grounded as shown in FIG. Alternatively, a variable direct current (DC) power supply may be connected to apply a predetermined direct current (DC) voltage to the gas shower head 25.

  A gas inlet 45 for introducing a gas is formed in the gas shower head 25. Inside the gas shower head 25, a diffusion chamber 50a at the center side and a diffusion chamber 50b at the edge side branched from the gas inlet 45 are provided. The gas output from the gas supply source 15 is supplied to the diffusion chambers 50a and 50b through the gas inlet 45, diffused in the respective diffusion chambers 50a and 50b, and supplied from the multiple gas supply holes 55 to the mounting table 20. Be introduced towards

  An exhaust port 60 is formed on the bottom of the chamber 10, and the inside of the chamber 10 is exhausted by an exhaust device 65 connected to the exhaust port 60 via an exhaust pipe. Thereby, the inside of the chamber 10 can be maintained at a predetermined degree of vacuum. A gate valve G is provided on the side wall of the chamber 10. Loading and unloading of the wafer W from the chamber 10 are performed by opening and closing the gate valve G.

  The etching apparatus 1 is provided with a control unit 100 that controls the operation of the entire apparatus. The control unit 100 includes a central processing unit (CPU) 105, a read only memory (ROM) 110, and a random access memory (RAM) 115. The CPU 105 executes desired processing such as etching described later according to various recipes stored in these storage areas. The recipe contains control information of the device for process conditions, process time, pressure (gas exhaust), high frequency power and voltage, various gas flow rates, chamber temperature (upper electrode temperature, chamber sidewall temperature, electrostatic chuck temperature, etc.) , The temperature of the chiller 107, etc. are described. In addition, the recipe which shows these programs and process conditions may be memorize | stored in a hard disk or semiconductor memory. Further, the recipe may be set at a predetermined position of the storage area in a state of being accommodated in a portable computer-readable storage medium such as a CD-ROM, a DVD, or the like.

  During the etching process, the opening and closing of the gate valve G is controlled, and the wafer W is carried into the chamber 10 and mounted on the mounting table 20. By supplying a direct current from the direct current voltage source 112 to the chuck electrode 106a, the wafer W is attracted to and held by the electrostatic chuck 106 by the coulomb force.

  Then, an etching gas, a high frequency power HF for plasma excitation, and a high frequency power LF for biasing are supplied into the chamber 10 to generate plasma. A plasma etching process is performed on the wafer W by the generated plasma.

  After the etching process, the DC voltage source 112 applies a DC voltage HV, which is opposite in polarity to the chucking of the wafer W, to the chuck electrode 106 a to remove the charge of the wafer W, and the wafer W is peeled off from the electrostatic chuck 106. The opening and closing of the gate valve G is controlled, and the wafer W is unloaded from the chamber 10.

[Etching method]
The etching method of one embodiment of the present invention is described. For example, as shown in FIG. 2A, the poly (polycrystalline) silicon film 12, which is the film to be etched, is etched using the silicon oxide film (Sio ₂ ) as the mask 11. However, the film to be etched is not limited to the polysilicon film 12, and may be, for example, an amorphous silicon film or a single crystal layer. The film to be etched may be a silicon oxide film or a silicon nitride film (SiN). The mask 11 may be an oxide film or a nitride film. Examples of the base film 13 of the polysilicon film 12 include a silicon oxide film, a silicon nitride film, and the like.

  FIG. 2 (a) shows an example of the structure of a film formed on a substrate before etching, and FIG. 2 (b) shows an example of the cross section of the etching shape of holes formed in the polysilicon film 12 after etching. Show.

  The aspect ratio is defined as the ratio of the top CD of the polysilicon film 12 to the depth D of the polysilicon film 12. For example, if the aspect ratio is about 15 to 20, even if a good etching shape can be obtained as shown in FIG. 2B, a good etching shape can be obtained if the aspect ratio 25 to 30 required in recent years There is no such thing. In particular, it is remarkable at 30 or more. As a result, as shown in FIG. 2C, twisting occurs, which is a phenomenon in which the tip (bottom side of the hole) of the etched hole is bent (bent, bent). Hereinafter, the process conditions for solving the problem of twisting and the etching method of one aspect of the present invention based on the process conditions will be described while comparing the process conditions of the comparative example and the present embodiment.

In the etching of the film configuration of FIG. 2A, the main etching for etching the polysilicon film 12 and the over etching for etching the base film 13 are performed. For example, hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen gas (O ₂ ) are used as an etching gas (first process conditions). The polysilicon film 12 is etched through the mask 11 by plasma generated from these gases under the first process conditions. Subsequently, overetching is performed to etch the underlayer 13 under the first process conditions. The etching method according to the present embodiment is suitable, for example, in the manufacture of a three-dimensional stacked semiconductor memory such as a 3D NAND flash memory.

The etching method according to the present embodiment is performed after about 10 seconds of removing the native oxide film on the polysilicon film 12 through the mask 11 by plasma generated from CF ₄ gas and O ₂ gas. Then, the polysilicon film 12 is etched.

[Etching method according to comparative example]
The etching method according to the comparative example will be described below. An example of process conditions at the time of etching the polysilicon film 12 in the comparative example is shown below.
・ Pressure 80mT (10.7Pa)
・ High frequency power HF 400W
・ High frequency power LF 2350 W pulse wave (frequency 0.1 kHz, duty ratio 30%)
・ Gas HBr / NF ₃ / O ₂
Etching time 90 seconds Temperature of mounting table 20 65 ° C.
In the etching according to the comparative example, after the polysilicon film 12 is main-etched, the base film 13 is over-etched by, for example, about 30%. In the comparative example, as shown in FIG. 3A, HBr gas, NF ₃ gas and O ₂ gas are all supplied at a constant flow rate in main etching and over etching.

  In the plasma etching under the above process conditions, when the aspect ratio is about 15, as shown in FIG. 2B, the etching shape of the polysilicon film 12 is processed almost vertically. However, when the aspect ratio is increased to, for example, 20, twisting as shown in FIG. 2C occurs, and the etched shape becomes worse.

  FIG. 4A shows an example of the etching result according to the comparative example under the above process conditions. As shown in FIG. 4 (a), twisting is not a problem when the aspect ratio is 15 or less, but twisting starts to occur when the aspect ratio exceeds 15, and when the aspect ratio is 25 or more Sting becomes apparent. In particular, with the recent miniaturization of devices, the problem of twisting in etching with an aspect ratio of 25 or more has become an unacceptable level.

One of the causes of twisting is that silicon Si represented by the following reaction formula (1) and SiBr _x O _y , SiOF _x, etc., which are reaction products generated during the etching process, are excessively attached to the side walls of the holes. It is thought that the directionality of ion is disturbed by doing and changing.

Si + HBr + O ₂ + NF ₃ → SiF _x Br _y + + SiF ₄ + + NH ₃ + + SiBr _x O _y + + SiOF _x・ ・ ・ (1)
According to Reaction Scheme _{(1), SiF x Br y} , SiF 4, NH 3 is a volatile substance, but is exhausted to the outside of the chamber _{10, SiBr x O y, SiOF} x is the deposition of the material Yes, adhere to the side of the hole, etc.

  The temperature of the mounting table 20 was 65 ° C. under the above process conditions. On the other hand, when the temperature of the mounting table 20 is controlled to a high temperature of 100 ° C. and the main etching → over etching is performed without changing the other conditions among the above process conditions, it adheres to the wall of the hole The amount of deposit decreased, etching of the hole proceeded, and bowing occurred in which the side of the hole spread, and a good etched shape was not obtained.

[Etching method according to the present embodiment]
Therefore, in the etching method according to the present embodiment, in addition to controlling the temperature of the mounting table 20 to 100 ° C. in the above process conditions, as shown in FIG. Vary. Specifically, the flow rates of HBr gas and O ₂ gas are varied while controlling the flow rate of NF ₃ gas constant.

  In the etching method of the present embodiment, as shown in FIG. 2B, the first to third steps obtained by roughly dividing the main etching of the polysilicon film 12 into three roughly and the fourth step of the over-etching of the base film 13 Each gas flow rate is controlled in four steps of. Gas flow control is performed by the control unit 100.

Specifically, in the first step of FIG. 3B, the flow rates of HBr gas, NF ₃ gas, and O ₂ gas are set to initial values. HBr gas is a gas mainly for promoting etching, and is a main etching gas. The NF ₃ gas is a gas mainly for removing deposits adhering to the mask 11. The O ₂ gas is a gas mainly for protecting the walls of the holes of the mask 11 and the polysilicon film 12.

Boeing tends to occur as the flow rate of HBr gas increases, and also tends to occur as the flow rate ratio of HBr gas to O ₂ gas increases. Therefore, in order to suppress bowing in the etching of the polysilicon film 12, it is preferable to increase not only the flow rate of HBr gas but also the flow rate ratio of O ₂ gas to HBr gas.

  Specifically, as shown in FIG. 3B, the flow rate of HBr gas in the first and second steps is controlled to be larger than the flow rate of HBr gas in the third and fourth steps. This promotes etching in the first and second steps. Further, the flow rate of the HBr gas is controlled to decrease stepwise in the second step to the fourth step. Thus, the etching is suppressed stepwise and the bowing formed in the holes is suppressed. The flow rate of HBr gas in the first and second steps may be the same, and may be decreased and increased stepwise.

Furthermore, by controlling the flow rate of the O ₂ gas in the second step to be higher than the flow rate of the O ₂ gas in the first step, the flow ratio of the O ₂ gas to the HBr gas is increased, and Protect the wall of the formed hole.

Furthermore, the flow rate of O ₂ gas in the third and fourth steps is slightly smaller than the flow rate of O ₂ gas in the second step. Also, the flow rate of the O ₂ gas in the third and fourth steps may be the same as the flow rate of the O ₂ gas in the second step, or may be decreased stepwise, or may be increased. good. In addition, here, the flow rate of the HBr gas is gradually decreased in the second step to the fourth step. Thereby, in the second to fourth steps, the flow ratio of O ₂ gas to HBr gas gradually increases. This makes it possible to suppress the bowing more effectively.

As described above, in the present embodiment, the flow rate of O ₂ gas is varied according to the flow rate of HBr. Specifically, in order to suppress bowing, the flow ratio of O ₂ gas to HBr gas is controlled to be gradually increased. In FIG. 3B, the O ₂ gas is controlled to the same flow rate in the third and fourth steps, but is not limited thereto. For example, as shown in FIG. 3 (c), while the flow ratio of O ₂ gas to HBr gas is increased stepwise from the first step to the fourth step, the occurrence of twisting is suppressed while the bowing is also suppressed. You can do it. The etching step is preferably performed in at least two steps or more, and more preferably three steps or more. The control of the flow ratio of HBr gas to O ₂ gas varies depending on the temperature of the mounting table 20 and the structure of the sample.

Further, the flow rate of the NF ₃ gas may be controlled to be constant in all steps as shown in FIG. 3 (b). Also, the present invention is not limited to this. For example, control may be performed at a constant level in the first and second steps, and may be controlled to gradually increase in the third and fourth steps. In addition, the flow rate of the O ₂ gas may be controlled to increase as the flow rate of the NF ₃ gas increases. This can promote the formation of a protective film that protects the side walls of the holes while removing deposits attached to the mask 11. Also, SF ₆ (sulfur hexafluoride) gas may be supplied instead of NF ₃ gas.

  An example of the etching result according to the present embodiment is shown in FIG. Compared with the case of FIG. 4 (a) of the result of the comparative example in which the flow rate of each gas is controlled to be constant and the temperature of the mounting table 20 is controlled to 100 ° C. as shown in FIG. 3 (a) It can be seen that the occurrence of In particular, in FIG. 4B, the occurrence of twisting can be prevented even if the aspect ratio is 25.

As described above, according to the etching method of the present embodiment, the temperature of the mounting table 20 is controlled to a high temperature of, for example, 100 ° C., and the flow rate of the etching gas in the plurality of etching steps (first to fourth steps) Vary. That is, among the gases supplied into the chamber 10, the HBr gas is reduced stepwise. Further, in the present etching method, the flow rate of O ₂ gas is controlled so that the flow rate ratio of O ₂ gas to HBr gas becomes higher as the etching progresses. Furthermore, the flow rate of NF ₃ gas is controlled to be constant in all steps, or is increased as the flow rate of O ₂ gas is increased. This suppresses the occurrence of twisting (see FIG. 2 (c)) and the occurrence of bowing (see FIG. 5 (a)) in etching, as shown in FIG. 5 (b). The etching shape can be formed substantially vertically.

The flow of the etching method according to the present embodiment will be briefly described with reference to FIG. When this process is started, the control unit 100 supplies CF ₄ gas and O ₂ gas into the chamber 10, and the natural oxide film of the mask 11 on the substrate is generated by plasma generated from the CF ₄ gas and O ₂ gas. Are removed (step S10).

Next, the control unit 100 supplies HBr gas, NF ₃ gas and O ₂ gas into the chamber 10 and etches the polysilicon film 12 by plasma generated from HBr gas, NF ₃ gas and O ₂ gas (see FIG. Step S12). However, another gas such as an inert gas may be added to the HBr gas, the NF ₃ gas and the O ₂ gas.

Next, the control unit 100 determines whether the first step of the etching has ended (step S14). When it is determined that the first step is completed, the control unit 100 reduces the flow rate of HBr gas stepwise in the second to fourth steps (step S16). Next, in the second to fourth steps, the control unit 100 gradually increases the flow rate of O ₂ gas to HBr gas (step S18), and ends the present process. Thereby, the etching shape of the holes formed in the polysilicon film 12 can be improved.

[Modification]
Next, an etching method according to a modification of the above embodiment will be described. In this modification, in order to improve twisting, the control region of the high frequency power LF for bias is optimized.

Specifically, for example, the upper limit value of the control region of the conventional high-frequency power LF for bias was less than 1500 W. On the other hand, in the present modification, the control unit 100 controls the high frequency bias power LF in the range of 4000 W to 10000 W, which is higher than the conventional one. For example, FIG. 7 shows an example of the etching method and twisting state according to the modification of the present embodiment. Process conditions used for the etching method of this modification are as follows.
・ Pressure 30mT (4.00Pa)-90mT (12.0Pa)
・ High frequency power HF 300 to 700 W
・ High frequency power LF 3000 W, 4500 W, 7000 W (pulse wave (frequency 0.1 kHz, duty ratio 20%))
・ Gas HBr / NF ₃ / O ₂
Etching time 90 seconds Temperature of mounting table 20 65 ° C. to 100 ° C.
The frequency of the pulse wave of the high frequency power LF for bias may be in the range of 0.1 kHz to 50 kHz. Also, the duty ratio may be in the range of 5% to 30%.

  FIG. 7 shows the results when a pulse wave of high frequency power LF for bias is applied at each power of 3000 W, 4500 W and 7000 W. The horizontal axis of FIG. 7 is a bottom CD. As shown in FIG. 8, the bottom CD is the diameter of the bottom of the hole formed in the polysilicon film 12. The middle is 12% smaller and the small 25% smaller than the large shown in the horizontal axis of FIG.

  The vertical axis in FIG. 7 is a twisting value. The twisting value is a deviation (3σ) indicating the variation of the distance between the holes from the shape (footprint) of the bottom of the hole whose example is shown in FIG. In the example of FIG. 8, the twisting value is higher when the high frequency bias power LF is low (Low Power) than when the high frequency bias power LF is higher (High Power).

  According to the result in FIG. 7, when a pulse wave of high frequency power LF for bias of 3000 W is applied, the twisting value is worse as the bottom CD becomes closer to "Small". This is because as the bottom CD becomes smaller, as ions in the plasma move in the thin hole, it becomes difficult to reach the bottom of the hole as shown in (1) of FIG. 9 (a) and reaches the bottom of the hole This is because the twisting occurs due to the front curve.

  On the other hand, when the pulse wave of the high frequency power LF for bias of 4500 W and 7000 W is applied, the bottom CD becomes "Small" compared to the case where the pulse wave of the high frequency power LF for bias of 3000 W is applied. However, the twisting value is less likely to deteriorate. That is, the twisting caused by the ions bending near the bottom of the hole is improved. This is because the value of high frequency power LF for bias is increased, and as shown in FIG. 9B, the ion energy becomes high, the straightness of the ions is enhanced, and the number of ions reaching near the bottom of the hole is It is because it could be increased.

  The high frequency bias power LF is a pulse wave, and the high frequency power LF for bias is applied between on and off. Thus, etching can be promoted while the high frequency bias power LF is on, and the gas in the hole can be exhausted out of the hole while the high frequency bias power LF is off. Thus, it is possible to prevent mask clogging in which the opening of the mask film 11 shown in (2) of FIG. 9A becomes narrow due to the reaction product at the time of etching. Further, it is possible to prevent necking in which a reaction product adheres to the side surface of the hole shown in (3) of FIG. This makes it easier for the ions to reach the bottom of the hole.

  As described above, according to the etching method according to the present modification, by applying a pulse wave of high frequency power LF for bias of 4000 W or more, the ion energy in the plasma is increased, and the ions are at the bottom of the hole. Make it easy to reach. Thereby, twisting can be improved, the etching shape can be improved, and etching of holes can be promoted. As a result, holes or grooves having an aspect ratio of 20 to 25, preferably 25 or more can be favorably etched.

In the etching method according to the present modification, as shown in FIG. 3B, the control of the HFr gas, NF ₃ gas, and O ₂ gas of the above embodiment is performed while the control of the high frequency power LF for bias is performed. You may go. Alternatively, as shown in FIG. 3A, the HFr gas, the NF ₃ gas, and the O ₂ gas of the above embodiment may be controlled to be constant while the high frequency power LF for bias may be controlled.

  As mentioned above, although the etching method and the etching apparatus were demonstrated by the said embodiment, the etching method and etching apparatus concerning this invention are not limited to the said embodiment, A various deformation | transformation and improvement are possible within the scope of the present invention It is. Matters described in the above plurality of embodiments can be combined without contradiction.

  For example, the temperature of the substrate is preferably 100 ° C. or higher, and more preferably in the range of 100 ° C. to 200 ° C. The temperature of the substrate may be the temperature of the mounting table 20 (surface temperature) or the temperature of the electrostatic chuck 106.

  Further, the etching apparatus using the etching method according to the present invention is applicable not only to capacitively coupled plasma (CCP: Capacitively Coupled Plasma) apparatuses but also to other etching apparatuses. Other etching apparatuses include inductively coupled plasma (ICP: Inductively Coupled Plasma), plasma processing apparatus using a radial line slot antenna, Helicon Wave Plasma (HWP) apparatus, electron cyclotron resonance plasma (ECR) An electron cyclotron resonance plasma) apparatus or the like may be used.

  The substrate processed by the etching apparatus according to the present invention is not limited to a wafer, and may be, for example, a large substrate for flat panel display, a substrate for EL element or solar cell.

1: etching apparatus 10: chamber 11: mask 12: polysilicon film 13: underlayer 15: gas supply source 20: mounting table 20 (lower electrode)
25: Gas shower head (upper electrode)
30: power supply device 100: control unit 106: electrostatic chuck

Claims (10)

An etching method for etching a silicon film formed on a substrate, comprising:
A plurality of gases including hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen (O ₂ ) gas are supplied into the chamber and a silicon film is etched by plasma generated from the supplied gas. Have a process,
The hydrogen bromide gas flow rate is reduced stepwise in two or more steps including the last one of the plurality of steps,
Adjusting the flow rate of the oxygen gas according to the decrease of the hydrogen bromide gas;
Etching method. Gradually increase the flow rate of the oxygen gas,
The etching method according to claim 1 . Increasing the flow ratio of oxygen gas to hydrogen bromide gas stepwise;
The etching method according to claim 1 or 2. Make the flow rate of the nitrogen trifluoride gas constant or increase;
When the flow rate of the nitrogen trifluoride gas is increased, the flow rate of the oxygen gas is increased according to the increase of the nitrogen trifluoride gas,
The etching method according to any one of claims 1 to 3 . The temperature of the substrate is adjusted to 100 ° C to 200 ° C.
The etching method as described in any one of Claims 1-4 . In the plurality of steps, a pulse wave of high frequency power LF for bias of 4000 W or more is applied,
The etching method as described in any one of Claims 1-5. The frequency of the pulse wave of the high frequency bias power is 0.1 kHz to 50 kHz, and the duty ratio is 5% to 30%.
The etching method of Claim 6 . An etching apparatus having a control unit and etching a silicon film formed on a substrate, the etching apparatus comprising:
The control unit
A plurality of gases including hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen (O ₂ ) gas are supplied into the chamber and a silicon film is etched by plasma generated from the supplied gas. In the process, the flow rate of the hydrogen bromide gas is reduced stepwise;
Adjusting the flow rate of the oxygen gas according to the decrease of the hydrogen bromide gas;
Etching equipment. An etching method for etching a silicon film formed on a substrate, comprising:
A plurality of gases including hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen (O ₂ ) gas are supplied into the chamber and a silicon film is etched by plasma generated from the supplied gas. Have a process,
The flow rate of the hydrogen bromide gas is decreased stepwise in the plurality of steps, and the flow rate of the oxygen gas is adjusted according to the decrease of the hydrogen bromide gas, and a pulse of the RF power LF for bias of 4000 W or more Apply a wave,
Etching method. An etching apparatus having a control unit and etching a silicon film formed on a substrate, the etching apparatus comprising:
The control unit
A plurality of gases including hydrogen bromide (HBr) gas, nitrogen trifluoride (NF ₃ ) gas and oxygen (O ₂ ) gas are supplied into the chamber and a silicon film is etched by plasma generated from the supplied gas. Have a process,
The flow rate of the hydrogen bromide gas is decreased stepwise in the plurality of steps, and the flow rate of the oxygen gas is adjusted according to the decrease of the hydrogen bromide gas, and a pulse of the RF power LF for bias of 4000 W or more Apply a wave,
Etching equipment.

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