Dry-method photoresist removing equipment and method for reducing damage of metal nitride

Abstract

The invention provides a dry-method photoresist removing device and method for reducing metal nitride damage, and the device comprises a Grid base which is provided with a plurality of first air inlets and second air inlets penetrating through the Grid base, and is disposed in the Grid base; the third air inlets communicate with the second air inlets. Plasmas are introduced into the first air inlet to the photoresist removing cavity; h2 is introduced into the second air inlet and enters the photoresist removing cavity through the third air inlet. According to the method, the normal photoresist removing quality is ensured, and meanwhile, the oxidation and damage to the metal nitride under the photoresist layer PR are reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor wafer manufacturing, and particularly relates to a dry stripping equipment and method for reducing damage to metal nitride. BACKGROUND

[0002] Metal nitride layers are widely used in semiconductor manufacturing processes. For example, in high dielectric constant metal gate (HKMG) processes, TiN / TaN is used as a work function layer or a barrier layer; in copper interconnection (Cu Damascene) processes, TaN / TiN is used as a diffusion barrier layer; and in 3D NAND and DRAM memory devices, metal nitride (such as TiN) is widely used as a charge trapping layer or an electrode.

[0003] Currently, semiconductor stripping equipment mainly uses a single step to remove photoresist by introducing a large amount of oxygen and nitrogen into the stripping cavity to cause a gray incineration reaction. This method can cause oxidation and damage to the metal nitride layer under the photoresist, thereby affecting the reliability of the process device and even causing device failure. In traditional metal nitride (such as TiN) stripping, a large amount of oxygen and nitrogen is introduced into the stripping cavity, and an oxidation reaction occurs between the lower metal nitride and the plasma. The following defects exist: 1) After stripping, a thick layer of metal oxide TiO2 is usually formed on the surface of the metal nitride, which changes the original electrical properties of the metal nitride. 2) Because the atomic radii of oxygen and nitrogen are large, the dissociation will also cause damage to the lower metal nitride. Therefore, it is necessary to avoid oxidation and reduce damage to the metal nitride as much as possible. SUMMARY

[0004] The purpose of the present application is to provide a dry stripping equipment and method for reducing damage to metal nitride, which can avoid oxidation and damage to the metal nitride under the photoresist layer (photoresist layer PR) as much as possible while ensuring normal stripping quality. The technical solution adopted is as follows: A dry stripping equipment for reducing damage to metal nitride, comprising a Grid base 5, a plurality of first gas inlets 51 are formed through the Grid base 5, further comprising: a second gas inlet 52 formed in the Grid base 5; a plurality of third gas inlets 53 in communication with the second gas inlet 52; The first gas inlet 51 is connected to the stripping cavity 8 by introducing plasma. The second gas inlet 52 is connected to the stripping cavity 8 by introducing H2 from the third gas inlet 53.

[0005] Preferably, further comprising: The bottom opening plasma cavity 4, the Grid base 5 at the bottom of the plasma cavity 4, and the carrier 7 below the Grid base 5; The carrier 7 is placed with a wafer 6 to be stripped, and the carrier 7 is movable in the stripping cavity 8; The Grid base 5 is arranged in the stripping cavity 8. The top of the plasma cavity 4 is provided with a gas inlet disc 3 for mixed gas.

[0006] Preferably, the plasma includes plasma N+ and plasma He+.

[0007] Preferably, the second gas inlet 52 includes a first channel 521, an annular channel 522, and a second channel 523 connected in sequence. The second channel 523 is connected with the third gas inlet 53.

[0008] A dry stripping method for reducing damage to metal nitride, based on the dry stripping equipment for reducing damage to metal nitride, comprising the following steps: The plasma and H2 are introduced into the stripping cavity 8. Preferably, the plasma includes plasma N+ and plasma He+. During the introduction into the stripping cavity 8, the plasma and H2 are not mixed.

[0009] Preferably, during the dissociation to form the plasma, the RF pulse power is 3000-6000W, and the RF pulse generation time is 1-100s.

[0010] Preferably, before the plasma and H2 are introduced into the stripping cavity 8, the following steps are further included: Step S01, forming a metal nitride layer on a Si substrate, and then forming a photoresist layer PR on the metal nitride layer. Step S02, opening the photoresist layer PR by lithography to expose part of the metal nitride layer. Step S03, performing stripping etching to make the photoresist layer PR remain on the metal nitride, and generating metal oxide at the same time.

[0011] Compared with the prior art, the advantages of the present application are: 1. The original Grid base is improved to realize the combination of top gas inlet and side gas inlet, realize the dissociation mode of H2 collision penning reaction, and the energy of H ion radicals is lower, and the reaction with metal nitride such as TiN on the substrate is weaker.

[0012] Specifically: After H2 dissociates, H ions react with the photoresist on the wafer surface to achieve the photoresist removal effect, and reduce the generated TiO2 to regenerate TiN.

[0013] 2. The diameter of the No. 3 air inlet 53 is smaller than that of the No. 1 air inlet 51. The No. 1 air inlet 51 is not a through hole.

[0014] Therefore, the No. 3 air inlet 53 is not connected to the No. 1 air inlet 51, and the No. 3 air inlet 53 is not connected to the plasma chamber 4.

[0015] Therefore, the plasma from the N2 and He dissociation at the top of the Grid base 5 bombards the H2 that comes out from the No. 3 air inlet 53.

[0016] If H2 enters from the first air inlet 51 and plasma N + Plasma He + The H2 particles enter the descaling chamber 8 together. Since the first air inlet 51 is a through hole, H2 may drift into the quartz tube plasma chamber 4 above the Grid base 5 and dissociate directly, thus gaining greater energy. This would cause greater damage to the wafer in the descaling chamber 8.

[0017] Specifically: If H2 dissociates within plasma chamber 4, it will generate H+ with higher energy than H2. + ; while in the degelatinized cavity 8, collisional dissociation occurs, and plasma N + Plasma He + Some of the energy will be lost.

[0018] Therefore, H2, N2, and He directly dissociate in the plasma chamber 4 and enter the degumming chamber 8, which results in greater energy being obtained in the degumming chamber 8 compared to the solution of the present invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the existing metal nitride removal method. Figure 2 This is a schematic diagram of the adhesive removal method of the present invention; Figure 3 Time series plot of source power and gas flow rate over time; Figure 4 Structural diagram of a dry degumming device for reducing metal nitride damage; Figure 5 A comparison chart showing the TiN loss amount between the adhesive removal method of this patent and existing adhesive removal methods; Figure 6 This is a partial sectional view of the Grid base; Figure 7 This is a top view of the Grid base; Figure 8This is a top view of the No. 2 air intake.

[0020] Among them, 1-RF radio frequency generator; 2-RF radio frequency matching components; 3-Intake disc; 4-Plasma chamber, 5-Grid base 51-No. 1 air intake, 52 - Second air intake, 521 - First channel, 522 - Annular channel, 523 - Second channel. 53-No. 3 air intake; 6-Wafer to be de-resined; 7-Stage, 8-Glue removal cavity. Detailed Implementation

[0021] The dry desmearing apparatus and method for reducing metal nitride damage according to the present invention will be described in more detail below with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0022] A dry desmearing apparatus for reducing metal nitride damage, comprising: The grid base 5 has several No. 1 air inlets 51 that penetrate through the grid base 5 along the thickness direction. The second air intake 52 is located inside the Grid base 5; Several No. 3 air inlets 53 are connected to No. 2 air inlets 52.

[0023] The plasma chamber 4 has an opening at the bottom, a grid base 5 located at the bottom of the plasma chamber 4, and a stage 7 located below the grid base 5; the plasma chamber 4 is a quartz cylinder.

[0024] The stage 7 holds the wafer 6 to be de-resisted; the stage 7 can move within the de-resisting chamber 8. The Grid base 5 is disposed on the adhesive removal cavity 8; the connection method between the Grid base 5 and the adhesive removal cavity 8 is existing technology.

[0025] The top of the plasma chamber 4 is provided with an air inlet plate 3 for the mixed gas to pass through.

[0026] The air intake plate 3 is located at the center of the plasma cavity 4, and its upper end is connected to the process gas pipeline. The air intake plate 3 is provided with small air holes to spray process gas into the plasma cavity 4.

[0027] The connection method between the air intake plate 3 and the process gas pipeline is existing technology.

[0028] The air intake plate 3 is fixed to the inner wall of the plasma chamber 4.

[0029] Plasma is introduced into the first air inlet 51; H2 is introduced into the second air inlet 52, and H2 enters the degumming chamber 8 through the third air inlet 53.

[0030] like Figures 6~8 The image shown is for illustrative purposes only. The second air intake 52 includes a first channel 521, an annular channel 522 and a second channel 523 connected in sequence; the second channel 523 is connected to the third air intake 53.

[0031] More specifically: A wafer is provided, on which a stack of films is covered, including a metal nitride film and a photoresist layer PR.

[0032] The intake disc 3 and the second intake port 52 both open and close periodically.

[0033] The opening and closing cycle of intake disc 3 is consistent with the opening and closing cycle of intake port 52.

[0034] RF generator 1 is periodically turned on and off to generate periodic RF pulse waves.

[0035] Both ends of the second air inlet 52 are connected to an air inlet pipe, which is equipped with a solenoid valve. The solenoid valve contains a signal receiver. The air inlet pipe extends to the outside of the cavity 8. The periodic gas switching of 52 is controlled by the solenoid valve. When the signal receiver inside the solenoid valve is at a high level, the solenoid valve is activated, and the gas is opened. When the signal is at a low level, the solenoid valve is deactivated, and the gas is closed.

[0036] 2. The gas inlet plate 3 (top air inlet) inside the quartz tube operates on the same principle as the second air inlet 52. The outlet is also equipped with a solenoid valve, which controls the periodic opening and closing of the outlet 3.

[0037] 3. The RF generator 1 is periodically turned on and off by using a low-frequency pulse signal. When the pulse signal is high, the power is on. When the pulse signal is low, the power is off.

[0038] The low-frequency pulse signal generated by the RF generator 1 is received by the solenoid valve signal receiver in the second air inlet 52 and the top air inlet 3, thereby producing a synchronous opening and closing effect.

[0039] When the RF generator 1 is turned on, N2 and He are first dissociated in the quartz tube due to the air intake at the top. The dissociated plasma passes through the lower Grid base 5 and then impacts the H2 air intake on the side, causing H2 to also dissociate and act on the wafer 6 below to be de-adhesived.

[0040] A dry adhesive removal method for reducing metal nitride damage includes the following steps: Step S0: Prepare the wafer to be de-resined 6.

[0041] Step S01: Form a metal nitride layer on a Si substrate, and then form a photoresist layer PR on the metal nitride layer; Step S02: Photolithography opens the photoresist layer PR, exposing part of the metal nitride layer; Step S03: Perform photoresist removal etching according to existing technology so that the photoresist layer PR remains on the metal nitride and a metal oxide layer is generated.

[0042] Step S1: N2 and He are introduced into the plasma chamber 4 through the air inlet plate 3; H2 is introduced into the second air inlet 52, and H2 enters the degumming chamber 8 through the third air inlet 53.

[0043] Specifically, a mixture of N2 and He gas at a flow rate of 3000-6000 sccm is introduced into the intake plate 3, and H2 gas at a flow rate of 1500-5000 sccm is introduced into the side of the Grid base 5. The pressure inside the plasma chamber 4 is 700-1000mT. It is electrically coupled to the RF generator 1 through the RF matching component 2, and the RF power is 3000-6000W to generate plasma.

[0044] For N2 and He, the top intake airflow is 3000-6000 sccm. For H2, the side intake uses a pulsed intake method with an airflow of 3000-6000 sccm. The pulse RF ON time is 1-100s, and the duty cycle is 1%-90%.

[0045] In step S2, N2 and He dissociate within plasma chamber 4 to form plasma N. + Plasma He + .

[0046] When the de-adhesive wafer 6 is placed on the stage 7, during the first 1-100 seconds, the top-inlet N2 / He gas first dissociates in the quartz cylinder under the action of the source power (upper radio frequency power).

[0047] Step 3: Remove photoresist.

[0048] Plasma N + Plasma He + It enters the degumming chamber 8 through the second air inlet 52 and impacts the H2 inside the degumming chamber 8 to cause H2 to disintegrate; After H2 dissociates, it reacts with the photoresist layer PR on the surface of the wafer 6 to be stripped, achieving the stripping effect and reducing the metal oxide.

[0049] likeFigure 1 As shown, existing metal nitride stripping methods involve oxygen and nitrogen being dissociated in a quartz cylinder via top-entry to bombard the wafer surface and remove the photoresist. This method typically uses oxygen at concentrations above 10,000 sccm and nitrogen at concentrations above 1,000 sccm, and the stripping time is relatively long. When dealing with processes below 28nm, this can damage and oxidize the underlying metal nitride layer, thus adversely affecting the entire wafer.

[0050] like Figure 2 As shown: The Grid base 5 employs a combination of top and side air intakes. N2 and He are introduced from the top of the Grid, where they first dissociate within the quartz cylinder to form plasma (N2). + He + H2 is introduced from the side, and the plasma formed at the top impacts the H2, causing ionization and forming hydrogen ions that bombard the lower wafer to remove the resist. This process reduces the ion energy density to some extent, thus mitigating oxidation and damage to the lower substrate.

[0051] like Figure 3 As shown, this is a time series diagram of the time variation of source power and gas flow rate.

[0052] The RF (radio frequency) system uses a pulsed start-up method, with the RF action lasting 1-100 seconds before stopping, then restarting for another 1-100 seconds before stopping, and so on. Similarly, the side-intake H2 and top-intake N2 and He systems also use a pulsed intake method, with the intake time and frequency consistent with the RF system. This plasma generation method results in a shorter single-pass effect on the wafer, avoiding damage to the wafer caused by prolonged resist removal.

[0053] Figure 5 As shown, when the desizing time is 180s, the existing desizing method results in a TiN loss of 11.5A, while the desizing method of this patent results in a TiN loss of 0.2A.

[0054] First, the initial film thickness of a TiN-coated wafer is measured. Then, the wafer undergoes 1800 seconds of both conventional and patented resist removal processes. Finally, the final film thickness of the TiN wafer is measured. The TiN thickness can be calculated by subtracting the thickness of the second film from the initial film thickness.

[0055] Therefore, the side-intake degumming chamber structure design and pulse dissociation method in this embodiment ensure the quality of degumming while having a lower damage effect on metal nitrides.

[0056] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A dry degumming device for reducing metal nitride damage, comprising a grid base (5) having a plurality of No. 1 air inlets (51) penetrating the grid base (5), characterized in that, Further includes: The second air intake (52) is located inside the Grid base (5); Several No. 3 air inlets (53) are connected to No. 2 air inlets (52); Plasma is introduced into the degumming chamber (8) through the first air inlet (51). H2 is introduced through the second air inlet (52), and H2 enters the degumming chamber (8) through the third air inlet (53).

2. The dry degumming equipment for reducing metal nitride damage according to claim 1, characterized in that, Further includes: A plasma chamber (4) with an opening at the bottom, a grid base (5) located at the bottom of the plasma chamber (4), and a stage (7) located below the grid base (5); The stage (7) on which the resist is to be removed is placed; the stage (7) can move within the resist removal chamber (8); The Grid base (5) is disposed in the glue removal cavity (8); The top of the plasma chamber (4) is provided with an air inlet plate (3) for the mixed gas to pass through.

3. The dry degumming equipment for reducing metal nitride damage according to claim 1, characterized in that, The plasma includes plasma N. + Plasma He + .

4. The dry degumming equipment for reducing metal nitride damage according to claim 1, characterized in that, The second air inlet (52) includes a first channel (521), an annular channel (522), and a second channel (523) connected in sequence. The second channel (523) is connected to the third air inlet (53).

5. A dry adhesive removal method for reducing metal nitride damage, based on the dry adhesive removal equipment for reducing metal nitride damage according to any one of claims 1 to 4, characterized in that, Includes the following steps: Plasma and H2 are introduced into the degumming chamber (8); Plasma includes plasma N + Plasma He + ; During the process of introducing the degumming chamber (8), the plasma and H2 do not mix.

6. The dry adhesive removal method for reducing metal nitride damage according to claim 1, characterized in that, During the dissociation process to form plasma, the RF pulse power is 3000-6000W and the RF pulse generation time is 1~100s.

7. The dry adhesive removal method for reducing metal nitride damage according to claim 1, characterized in that, Before introducing plasma and H2 into the degumming chamber (8), the following steps are also included: Step S01: Form a metal nitride layer on a Si substrate, and then form a photoresist layer PR on the metal nitride layer; Step S02: Photolithography opens the photoresist layer PR, exposing part of the metal nitride layer; Step S03: Perform photoresist removal etching to leave a photoresist layer PR on the metal nitride, while simultaneously generating a metal oxide.

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