Substrate pretreatment method and plasma etching device

Abstract

The invention discloses a substrate pretreatment method and a plasma etching device. The method comprises the following steps: providing a substrate with a radius R, wherein the substrate comprises a substrate and a mask layer to be processed on the substrate; the mask layer at least comprises an annular edge area; the substrate is placed in a reaction cavity of a plasma etching device, and the bias radio frequency power is set to be 0-50 W; introducing process gas into the plasma etching device; and controlling the chamber pressure of the plasma etching device according to the critical dimension distribution condition of the mask layer. According to the pretreatment method, the chamber pressure is adjusted based on the critical size distribution condition of the edge area so as to control the reaction rate of the edge area of the substrate, the pretreatment efficiency of the substrate can be more effectively improved, the process window is large, and the treated substrate is good in consistency.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor etching process, and in particular to a substrate pretreatment method and a plasma etching device. Background Art

[0002] The descriptions in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] In the field of semiconductor etching technology, the critical dimension (CD) of the mask has an important influence on the subsequent etching process window, etching morphology, etching rate, etching selectivity and other parameters. On the one hand, the initial size of the critical dimension of the mask will affect the subsequent etching process window and the critical dimension of the etched holes or grooves formed by etching; on the other hand, for the entire substrate, the uniformity of the critical dimension will affect the uniformity of the holes or grooves etched subsequently.

[0004] Taking the process of etching the silicon oxide layer to form a contact hole in 3D NAND and stopping on the silicon nitride (SiN) layer (stop layer) as an example, appropriately increasing the critical size of the mask will make it easier for the generated polymer to enter the bottom of the hole and deposit. The deposited polymer can protect the silicon nitride layer, thereby increasing the selectivity of silicon oxide to silicon nitride. However, the critical size of the mask cannot be too large, otherwise there will be too much polymer and it will accumulate at the bottom of the hole, which will easily cause the silicon oxide etching rate to slow down or even stop etching. Figure 1 As shown, the critical dimensions of the opening of the mask layer 10 on the substrate are small, medium and large. Through the opening of the mask layer 10, the pattern is transferred to the silicon oxide layer 20 to form three types of contact holes: small hole h1, medium hole h2 and large hole h3, and the critical dimension h1 < critical dimension h2 < critical dimension h3. In the process of etching to form the contact hole, the critical dimension of the medium hole h2 is moderate, the polymer can enter the bottom of the hole, and the thickness of the formed polymer protective layer 40 is moderate, which improves the selectivity of silicon oxide to silicon nitride and avoids the silicon nitride layer 30 from being etched through during the etching process; the critical dimension of the small hole h1 is small, the polymer is difficult to enter the bottom of the hole, the formed polymer protective layer 40 is very thin or almost non-existent, and cannot effectively protect the silicon nitride, and the silicon nitride layer 30 is etched through; while the critical dimension of the large hole h3 is large, the polymer can easily enter the bottom of the hole, and a thicker polymer protective layer 40 is formed, so that the etching of silicon oxide is delayed or even stopped, and the etching hole of the preset depth cannot be formed. It can be seen that controlling the critical size and uniformity of the mask layer is very important for the etching process.

[0005] There are requirements for the critical dimensions of the etched holes or grooves, and the non-uniform critical dimensions of the mask layer lead to insufficient subsequent etching process windows. The current common solution is to change the main etching process to change the critical dimensions of the etched holes or grooves, but this usually leads to unexpected changes in other key parameters. If you only want to change the critical dimensions of the mask layer, you need to cooperate with the process of preparing the mask layer in the front-end. However, the preparation process of the front-end mask layer itself is difficult to achieve uniform critical dimensions of the mask layer at different radii across the entire substrate. We found that especially in the edge area, the critical dimensions of the mask layer prepared by the front-end process in the edge area are usually quite different from those in other areas. Therefore, it is necessary to provide a simplified process flow for improving the subsequent etching process window, which does not involve changing the front-end mask layer process or changing the process parameters of the main etching.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solution of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above contents are well known to those skilled in the art simply because they are described in the background technology section of the present invention. Summary of the invention

[0007] The purpose of the present invention is to provide a substrate pretreatment method for in-situ modification of the pattern of the mask layer so as to make the key dimensions of the mask layer uniform, thereby making the key dimensions of the device formed by transferring to the substrate consistent.

[0008] In order to achieve the above object, the present invention provides a substrate pretreatment method, comprising:

[0009] Providing a substrate with a radius of R, the substrate comprising a substrate and a mask layer to be processed on the substrate; the mask layer at least comprises an annular edge region, the inner diameter of the annular edge region is r, and r / R ≥ 0.9;

[0010] Placing the substrate in a reaction chamber of a plasma etching device, and setting the bias radio frequency power of the plasma etching device to 0-50W;

[0011] introducing a process gas into the plasma etching device;

[0012] The chamber pressure of the plasma etching device is controlled according to the distribution of the critical dimensions of the mask layer: when the average value of the critical dimensions of the edge area is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is a first pressure; when the average value of the critical dimensions of the edge area is less than the average value of the critical dimensions of the mask layer, the chamber pressure is a second pressure; the first pressure is less than the second pressure.

[0013] Optionally, the first pressure is 15mT to 50mT.

[0014] Optionally, the second pressure is 50mT to 300mT.

[0015] Optionally, the pretreatment method further comprises controlling the distribution of the process gas according to a critical dimension distribution of the mask layer.

[0016] Optionally, the process gas at least includes an etching gas, and a flow rate of the etching gas in each region of the mask layer is negatively correlated with a critical dimension of each region of the mask layer.

[0017] Optionally, the etching gas includes an oxidizing gas.

[0018] Optionally, the oxidizing gas includes at least one of oxygen, ozone, nitrogen and nitrogen-containing oxygen gas.

[0019] Optionally, the total flow rate of the etching gas introduced into the plasma etching device is 200 sccm to 1500 sccm.

[0020] Optionally, the process gas further includes a passivation gas, and the flow rate of the passivation gas in each region of the mask layer is positively correlated with the critical dimension of each region of the mask layer.

[0021] Optionally, the passivation gas includes at least one of a carbon fluorine gas and a carbon hydrofluorine gas.

[0022] Optionally, the passivation gas includes at least one of CF4, C4F6, C4F8, CH2F2, and CHF3.

[0023] Optionally, the flow rate of the passivation gas in each area of ​​the mask layer is 0 sccm to 30 sccm.

[0024] Optionally, a protective layer is further provided on the mask layer.

[0025] Optionally, the protective layer is a residual anti-reflection layer.

[0026] Optionally, the mask layer is a carbon-based mask, and the residual anti-reflection layer is a non-carbon-based residual layer.

[0027] Optionally, the pretreatment method further comprises adjusting at least one of a source RF power, a bias RF power and a pretreatment time of the plasma etching device according to a critical dimension of the mask layer.

[0028] Optionally, the source radio frequency power is 500W to 1500W.

[0029] Optionally, the preprocessing time is 15s to 120s.

[0030] Optionally, the edge area also includes an annular extreme edge area, the inner diameter of the annular extreme edge area is r2, the outer diameter is R, r2 / R≥0.98; wherein, the chamber pressure of the plasma etching device is controlled according to the distribution of the critical dimensions of the mask layer to be set as: when the average value of the critical dimensions of the extreme edge area is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is a first pressure; when the average value of the critical dimensions of the extreme edge area is less than the average value of the critical dimensions of the mask layer, the chamber pressure is a second pressure; the first pressure is less than the second pressure.

[0031] The present invention also provides a substrate processing method, comprising:

[0032] Performing the above-mentioned substrate pretreatment method on the substrate;

[0033] The pattern of the pre-treated mask layer is transferred to the substrate in the plasma etching device.

[0034] The present invention also provides a plasma etching device, comprising:

[0035] Reaction chamber;

[0036] A susceptor, which is arranged at the bottom of the reaction chamber and is used to carry a substrate with a radius of R; the substrate comprises a substrate and a mask layer to be processed on the substrate; the mask layer at least comprises an annular edge region, the inner diameter of the annular edge region is r, and r / R ≥ 0.9;

[0037] A gas supply component, the gas supply component at least comprising: a gas distributor and a gas shower head, the gas shower head is arranged at the top of the reaction chamber, opposite to the substrate; the gas shower head comprises a plurality of gas inlet channels, the gas shower head is divided into a plurality of regions in the radial direction, and the gas distributor is used to control the gas outlet flow rate of each region;

[0038] Source RF source;

[0039] Bias RF source;

[0040] extraction device; and

[0041] A control unit, wherein the control unit controls the plasma etching device to execute the substrate processing method as claimed in claim 19.

[0042] The gas shower head is divided into a central area, a middle area and an edge area in the radial direction; or, the gas shower head is divided into a central area, a middle area, an edge area and an extreme edge area in the radial direction.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] Since it is found that the edge area of ​​the substrate is more sensitive to pressure than the middle area or the center area, the reaction rate of the edge area of ​​the substrate changes significantly with the adjustment of the pressure. The pretreatment method of the present invention controls the reaction rate of the edge area of ​​the substrate by adjusting the chamber pressure, which can more effectively improve the pretreatment efficiency of the substrate, with a larger process window and good consistency of the treated substrate. Specifically, the present invention controls the chamber pressure according to the distribution of the critical dimensions of the mask layer, especially the critical dimensions of the edge area: when the critical dimensions of the edge area of ​​the mask layer are greater than the average value of the critical dimensions of the mask layer, it is necessary to minimize the graphic modification of the edge area, and a lower first pressure can be used; when the critical dimensions of the edge area of ​​the mask layer are less than the average value of the critical dimensions of the mask layer, it is necessary to enhance the graphic modification of the edge area, and a higher second pressure is used.

[0045] The present invention performs pretreatment of the substrate and subsequent etching process in the same processing chamber, and the substrate can be processed in situ after the pretreatment, thereby reducing the number of times the substrate is moved in and out of the chamber and saving the process flow.

[0046] Furthermore, the present invention also adjusts at least one of the distribution of process gas, source RF power, bias RF power or pretreatment time according to the critical size distribution of the mask layer to achieve the purpose of precise directional modification and improve the modification efficiency of the pattern.

[0047] The present invention utilizes the residual anti-reflection layer to protect the mask layer, thereby avoiding excessive consumption of the thickness of the mask layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the state of a substrate during a main etching process.

[0049] Figure 2 A cross-sectional view of a substrate to be processed.

[0050] Figure 3 The present invention is a flow chart of a substrate pretreatment method.

[0051] Figure 4 This is a graph showing the relationship between the reaction rate and the wafer radius when different flow rates of oxygen are introduced into different areas in the processing method of the present invention.

[0052] Figure 5 This is a graph showing the relationship between the reaction rate and the wafer radius when different flow rates of C4F6 gas are introduced into the central area in the processing method of the present invention.

[0053] Figure 6FIG. 4 is a graph showing the relationship between the reaction rate and the wafer radius under different chamber pressures in the processing method of the present invention.

[0054] Figure 7 A schematic diagram of the state of a substrate during pretreatment.

[0055] Figure 8 FIG. 4 is a diagram showing the relationship between the critical dimension and the radio frequency power in the processing method of the present invention.

[0056] Fig. 9 This is a diagram showing the relationship between the critical dimension and the pre-processing time in the processing method of the present invention.

[0057] Fig.10 The invention discloses a method for processing a substrate.

[0058] Fig.11 It is a schematic diagram of a plasma etching device of the present invention.

[0059] Figure ID:

[0060] Small hole h1

[0061] Middle hole h2

[0062] Large hole h3

[0063] Mask layer 10

[0064] Silicon oxide layer 20

[0065] Silicon nitride layer 30

[0066] Protective layer 40

[0067] Substrate 201, 701

[0068] Etching layer 202, 702

[0069] Mask layer 203, 703

[0070] Opening 204, 706

[0071] Central Area A1

[0072] Central area A2

[0073] Edge area A3

[0074] Active Particles 700

[0075] Anti-reflection layer 704

[0076] Photoresist layer 705

[0077] Substrate w

[0078] Plasma 1

[0079] Reaction chamber 110

[0080] Reaction chamber side wall 111

[0081] Base 112

[0082] RF power source 113

[0083] Gas sprinkler head 114

[0084] Gas distributor 115

[0085] Gas supply device 116

[0086] Air extraction device 117

[0087] Control unit 118. DETAILED DESCRIPTION

[0088] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0089] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0090] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0091] The present invention proposes to perform in-situ pretreatment on the substrate before the main etching process step, and adjust the reaction rate between the mask layer and the process gas in different areas according to the distribution of the key dimensions in different areas, so as to adjust the size and uniformity of the key dimensions of the mask layer. The present invention designs at least one of the following means to pretreat the substrate:

[0092] 1) controlling the chamber pressure of the plasma etching device according to the critical dimension distribution of the mask layer, thereby regulating the reaction rate of the edge area of ​​the substrate;

[0093] 2) controlling the distribution of the process gas according to the critical dimension distribution of the mask layer;

[0094] 3) adjusting at least one of the source RF power, bias RF power and pre-processing time of the plasma etching device according to the critical dimension of the mask layer.

[0095] The following is a detailed explanation with reference to the figures.

[0096] like Figure 2 The figure shows a cross-sectional view of a substrate to be processed according to the present invention. The substrate comprises an etching layer 202 and a mask layer 203 which are sequentially arranged on a substrate 201. The mask layer is provided with a plurality of openings 204 to form a pattern of the mask layer. The mask layer is divided into at least three regions within the radius R of the mask layer 203: a central region A1, a middle region A2 and an edge region A3. The central region A1 is a circular region with an edge radius of r1 centered at the center of the mask layer, the middle region A2 is an annular region with an inner diameter of r1 and an outer diameter of r, where r>r1; the inner diameter of the edge region A3 is r and the outer diameter is R. The mask layer covers the substrate substrate, and the radius is the same as that of the substrate, which is R. For example, for a substrate with a radius of 150 mm, the region within 70 mm can be set as the central region A1, the annular region with an inner diameter of 70 mm and an outer diameter of 135 mm can be set as the middle region A2, and the annular region outside 135 mm can be set as the edge region A3.

[0097] In some embodiments, the outermost area of ​​the edge area A3 is further divided into an extreme edge area. For a substrate with a radius of 150 mm, an annular area with an inner diameter r2 not less than 147 mm can be considered as an extreme edge area. That is, an annular area with r2 / R ≥ 0.98 can be considered as an extreme edge area.

[0098] like Figure 3 In the first embodiment shown, a substrate pretreatment method of the present invention comprises:

[0099] Step S1, providing a substrate with a radius of R, wherein the substrate comprises a substrate and a mask layer to be processed on the substrate; the mask layer at least comprises an annular edge region, the inner diameter of the annular edge region is r, and r / R≥0.9.

[0100] The mask layer to be processed has a certain opening pattern, but the critical size of the opening does not meet the requirements of the hole or groove of the device and needs preprocessing, for example, the size and / or uniformity of the opening does not meet the device requirements. We found that the critical size of the edge area of ​​the substrate usually deviates a lot from the average value, and it is necessary to perform targeted etching according to the distribution of the critical size of different areas, especially the edge area.

[0101] In the etching process, the substrate is selectively etched through the opening of the mask layer, and the opening pattern can be transferred to the substrate to form a hole or groove with a corresponding pattern. In some embodiments, an etching layer is provided on the substrate, and the etching layer is selectively etched through the opening of the mask layer to transfer the opening pattern to the etching layer. The etching layer can be a silicon oxide layer, but is not limited thereto.

[0102] Step S2, placing the substrate in a reaction chamber of a plasma etching device, and setting the bias radio frequency power of the plasma etching device to 0-50W.

[0103] In order to implement the subsequent etching process in situ after the substrate is pretreated, the pretreatment of the present invention is carried out in a plasma etching device.

[0104] The pretreatment of the present invention is carried out on the mask layer, mainly to fine-tune and modify the uneven parts of the key dimensions of the mask layer. In order to avoid excessive loss of the thickness of the mask layer and thus affect the subsequent main etching process, the modification process adopted is very gentle, mainly based on chemical reaction, and the physical bombardment is very weak. Therefore, the power of the bias radio frequency can be relatively small, or even 0, that is, the bias radio frequency is not turned on. The power of the bias radio frequency can be set according to the specific size distribution, and the power is generally set to not exceed 50W.

[0105] Step S3, introducing process gas into the plasma etching device.

[0106] The process gas at least includes an etching gas to selectively etch the sidewalls of the openings of the mask layer to expand or modify the size of the openings. The flow rate of the etching gas introduced into each area of ​​the mask layer is negatively correlated with the critical dimensions of each area of ​​the mask layer. For areas where the critical dimensions are lower than the average value of the critical dimensions of the mask layer, a larger flow rate of etching gas is introduced to increase the etching rate; for areas where the critical dimensions exceed the average value, a smaller flow rate or even no etching gas is introduced to reduce the etching rate. In some embodiments, a gas distributor of a plasma etching device can be used to introduce different flow rates of process gas into different areas of the mask layer.

[0107] The etching gas includes an oxidizing gas. The oxidizing gas includes at least one of oxygen, ozone, nitrogen and nitrogen-containing oxygen gas. Taking oxygen as an example, oxygen with different flow distributions (O2 distribution 1 and O2 distribution 2) is used as the etching gas. The flow rate of oxygen introduced into the central area A1 of the substrate in O2 distribution 1 is greater than that in O2 distribution 2. The reaction rate between the opening sidewall of the mask layer in each area on the substrate and the etching gas is tested. Figure 4 As shown, the reaction rate of the central area A1 on the substrate fed with O2 distribution 1 is significantly higher than that of the substrate fed with O2 distribution 2. It can be seen that the reaction rate between the opening sidewall of the mask layer and the etching gas is positively correlated with the flow rate of the etching gas.

[0108] In the method of the present invention, the total flow rate of the etching gas introduced into the plasma etching device is 200 sccm to 1500 sccm. The process gas introduced into the edge area A3 accounts for 10% to 90% of the total gas introduction amount.

[0109] In some embodiments, in order to slow down the etching rate of the opening with a larger critical dimension, the process gas further includes a passivation gas. The passivation gas includes a carbon fluoride gas (C x F y , x,y>0) and / or hydrocarbon-hydrofluorine gas (C x H y F z , x, y, z>0), for example, at least one of CF4, C4F6, C4F8, CH2F2, CHF3, etc., and the following is a detailed description using carbon fluorine gas as an example. For mask layer areas where the critical dimensions are larger than the average value or close to the critical dimension requirements of the device, the introduced process gas contains carbon fluorine gas as a passivation gas, and the carbon fluorine gas can form a polymer protective layer on the sidewall of the opening to prevent the opening from being etched and causing the critical dimensions to be further enlarged. The flow rate of the passivation gas introduced into each area of ​​the mask layer is positively correlated with the critical dimensions of each area of ​​the mask layer. Figure 5 As shown, using C4F6 as the passivation gas, 10 sccm of C4F6, 5 sccm of C4F6, and 0 sccm of C4F6 were introduced into the central area of ​​the substrate for testing. It can be seen that as the concentration of C4F6 increases, the reaction rate in the central area of ​​the substrate gradually decreases.

[0110] Therefore, for the area with a larger critical dimension, a larger flow of passivation gas is introduced to slow down the etching rate of the area and prevent the critical dimension from further expanding; for the area with a smaller critical dimension, a smaller flow of passivation gas is introduced, or even no passivation gas is introduced, so as not to reduce the pretreatment rate of the area. As an example, the flow rate of the passivation gas in each area of ​​the mask layer is 0 sccm to 30 sccm.

[0111] Moreover, the molar mass of the passivating gas of the present invention is greater than that of the oxidizing gas, and it is relatively difficult to diffuse. It can be directed into each area, and the gas distribution in each area can be accurately controlled.

[0112] Step S4, controlling the chamber pressure of the plasma etching device according to the distribution of the critical dimensions of the mask layer: when the average value of the critical dimensions of the edge area is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is a first pressure; when the average value of the critical dimensions of the edge area is less than the average value of the critical dimensions of the mask layer, the chamber pressure is a second pressure; the first pressure is less than the second pressure.

[0113] like Figure 6 As shown, under the larger second pressure, the reaction rate in the edge area is abnormally sensitive, and the reaction rate increases sharply as the radius increases. The present invention unexpectedly found that under the smaller first pressure, the reaction rate in the edge area is not sensitive to pressure, and the reaction rate increases slightly as the radius increases, and the reaction rate even decreases in the extreme edge area. Therefore, the present invention can adjust the chamber pressure of the pre-treated substrate according to the critical size of the edge area to solve the problem of uneven critical size of the substrate mask layer.

[0114] When the average value of the critical dimension of the edge region is greater than the average value of the critical dimension of the mask layer, in order to make the critical dimension uniform, it is hoped to etch the opening of the edge region as little as possible to avoid further expanding its critical dimension, so the first pressure is set to be relatively small, such as 15mT to 50mT.

[0115] When the average value of the critical dimension of the edge area is smaller than the average value of the critical dimension of the mask layer, in order to make the critical dimension of the mask layer uniform, it is hoped to etch as many openings in the edge area as possible, so the second pressure is set to be relatively large, such as 50mT~300mT. Under the second pressure, the etching rate of the openings in the edge area of ​​the mask layer is faster, and the critical dimension gradually expands, while the etching rate of the central area and the middle area of ​​the mask layer is slower. As the etching proceeds, the critical dimension of the mask layer gradually becomes uniform.

[0116] The reasons why the etching rate in the edge area changes sharply with pressure may be as follows. The free path of molecules reflects the distance that gas molecules can move without colliding with surrounding molecules. The molecular mean free path λ = kT / Pσ, where k is the Boltzmann constant, T is the absolute temperature of the gas, P is the gas pressure, and σ is the molecular collision cross section, which is related to the type of gas. For a fixed type of molecule, at a certain temperature, the mean free path of the molecule is inversely proportional to the pressure, that is, the smaller the pressure, the larger the mean free path, the larger the distance that the molecule can move, and the better the uniformity of the reaction rate in different regions.

[0117] The plasma etching device can control the chamber pressure by controlling the opening of the molecular pump. Under the same other conditions, the higher the gas pressure in the chamber, the smaller the volume of gas extracted from the chamber by the molecular pump per unit time. Since the molecular pump is usually set at the bottom edge of the base, close to the edge area of ​​the substrate. Therefore, within a certain range, when the chamber pressure is high, the gas concentration in the edge area of ​​the substrate (especially the extreme edge area) will be higher than that under the condition of low chamber pressure, and the reaction rate will be greater.

[0118] The above steps S2-S4 are shown as an example sequence, but it should be understood that there is no sequence restriction for steps S2, S3 and S4, that is, setting the RF power, introducing the process gas and controlling the chamber pressure can be performed in sequence as needed, and another or two steps can be performed during one step. For example, the chamber pressure can be adjusted during the process of introducing the process gas.

[0119] In order to further accurately control the etching rate of different regions, the pretreatment method also includes controlling the distribution of the process gas according to the distribution of the critical dimensions of the mask layer. For example, in each region of the mask layer, for the region with a larger critical dimension, a smaller flow of etching gas and a larger flow of passivation gas can be controlled to be introduced; for the region with a smaller critical dimension, a larger flow of etching gas can be controlled to be introduced, and no or a smaller flow of passivation gas can be introduced. In some embodiments, the distribution of the critical dimensions in each region of the mask layer can also be observed according to the etching situation, and the distribution of the process gas can be dynamically adjusted.

[0120] In the second embodiment, the difference from the first embodiment is that in step S1, the edge region may also include an annular extreme edge region, the inner diameter of the annular extreme edge region is r2, r2 / R≥0.98; in step S4, the chamber pressure of the plasma etching device is controlled to be changed according to the distribution of the critical dimensions of the mask layer: when the average value of the critical dimensions of the extreme edge region is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is the first pressure; when the average value of the critical dimensions of the extreme edge region is less than the average value of the critical dimensions of the mask layer, the chamber pressure is the second pressure; the first pressure is less than the second pressure. The remaining features are the same as those in the first embodiment.

[0121] In some embodiments, Figure 7As shown in a, the substrate to be preprocessed includes a substrate 701, an etching layer 702 is provided on the substrate 701, and a mask layer 703 is provided on the etching layer 702, and the mask layer may be a carbon-based mask layer, such as an amorphous carbon layer. An anti-reflection layer 704 is coated on the mask layer 703, and the anti-reflection layer 704 may be a non-carbon-based anti-reflection layer, such as silicon oxynitride (SiON). A photoresist layer 705 is provided on the anti-reflection layer 704. After the photoresist layer 705 is exposed to form a photolithography pattern, the anti-reflection layer 704 is etched using the photoresist layer 705 as a mask, and the pattern is transferred to the anti-reflection layer 704, exposing the mask layer 703 thereunder, and removing the photoresist layer 705; the pattern is transferred to the mask layer 703 using the anti-reflection layer 704 as a mask, and an opening 706 is formed, as shown in FIG. Figure 7 As shown in b, after the mask layer 703 is etched, the anti-reflection layer 704 will remain. Different from the prior art, the present invention does not remove the remaining anti-reflection layer 704, but immediately uses the method of the present invention to pre-treat the substrate, such as Figure 7 As shown in FIG. 3 , the residual anti-reflection layer 704 can be used as a protective layer for the mask layer 703. Under the masking of the protective layer, the active particles 700 formed by the process gas activated by the RF power can etch the sidewalls of the opening 706 of the mask layer 703 without losing the thickness of the mask layer 703. Figure 7 As shown in d, the critical dimensions of the mask layer 703 are uniform.

[0122] Since the bias RF power is low in the pretreatment of the present invention, the contour of the mask layer is modified mainly by chemical reaction, and the physical bombardment is weak, even if there is no anti-reflection layer 704 or other protective layer shielding the upper surface of the mask layer 703, the method of the present invention can be used to pretreat the substrate.

[0123] In some embodiments, the pretreatment of the critical dimension can also be controlled by adjusting the source RF power of the plasma etching device. Under the same other conditions, the magnitude of the source RF power is positively correlated with the concentration of the plasma formed in the chamber. If gentle etching is required, the source RF power can be lowered. The critical dimension of the mask layer formed by pretreatment is positively correlated with the source RF power, such as Figure 8 As shown, as the RF power is increased, the critical dimension gradually increases, and the linear relationship in the figure is only for example and is not limited thereto. In the present invention, the source RF power is 500W to 1500W, and the source RF frequency is 60MHz.

[0124] In some embodiments, the preprocessing of the critical dimension of the mask layer can also be controlled by the preprocessing time. The critical dimension of the mask layer formed by the preprocessing is positively correlated with the preprocessing time, such as Fig. 9As shown, the longer the pretreatment time is, the larger the critical dimension is. The linear relationship in the figure is only for example and is not limited thereto. In the present invention, the pretreatment time is 15s to 120s.

[0125] In some embodiments, at least one of the chamber pressure, the distribution of process gas in each area, the source RF power, the bias RF power and the pretreatment time may be comprehensively adjusted according to the distribution of the critical dimensions in each area of ​​the mask layer.

[0126] like Fig.10 As shown, the present invention also provides a substrate processing method, comprising:

[0127] Step S10.1, performing the above-mentioned substrate pretreatment method on the substrate to make the critical dimension of the mask layer uniform;

[0128] Step S10.2, transferring the pattern of the pre-treated mask layer onto the substrate in situ in the plasma etching device.

[0129] To implement the above substrate processing method, the present invention also shows a plasma etching device, such as Fig.11 As shown, the plasma etching device includes: a reaction chamber 110 and a reaction chamber side wall 111 surrounding the reaction chamber 110. A base 112 is arranged at the bottom of the reaction chamber 110 for carrying a substrate w with a radius R. The base 112 is also used as the lower electrode of the plasma etching device, which is connected to a radio frequency power source 113. In other embodiments, the radio frequency power source 113 can be added to the upper electrode. A gas shower head 114 is arranged at the top of the reaction chamber 110 opposite to the base 112, which also serves as the upper electrode of the plasma etching device. The radio frequency power applied by the radio frequency power source 113 forms an electromagnetic field between the upper electrode and the lower electrode, and the process gas injected into the reaction chamber 110 by the gas shower head 114 is ionized under the action of the electromagnetic field to generate plasma 1. The plasma 1 contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above active particles can undergo various physical and chemical reactions with the side wall surface of the mask layer of the substrate w, and etch the side wall of the mask layer of the substrate to complete the pretreatment process.

[0130] The plasma etching device further includes a gas supply assembly, which includes at least: a gas shower head 114, a gas distributor 115 and a gas supply device 116. The gas shower head 114 includes a plurality of gas inlet channels, and the gas shower head 114 is divided into a plurality of regions in the radial direction, for example, a central region A1, a middle region A2, and an edge region A3; in some embodiments, an extreme edge region may also be included. The gas distributor 115 is used to control the gas flow rate of each region.

[0131] The plasma etching device further comprises a gas extraction device 117, such as a vacuum pump. By controlling the opening of the gas extraction device 117, the chamber pressure in the reaction chamber can be controlled.

[0132] The plasma etching device further includes a control unit 118, and the control unit 118 controls the plasma etching device to execute the above-mentioned substrate processing method.

[0133] In summary, the present invention performs in-situ pretreatment on the substrate before the main etching process step, and can make targeted size and uniformity adjustments to the key dimensions of the mask layer without changing the mask process, simplifying the process flow and improving the subsequent etching process window.

[0134] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A substrate pretreatment method, characterized in that: include: Providing a substrate with a radius of R, wherein the substrate comprises a substrate and a mask layer to be processed located on the substrate; The mask layer at least includes an annular edge region, the inner diameter of the annular edge region is r, and r / R≥0.9; Placing the substrate in a reaction chamber of a plasma etching device, and setting the bias radio frequency power of the plasma etching device to 0-50W; introducing a process gas into the plasma etching device; The chamber pressure of the plasma etching device is controlled according to the distribution of the critical dimensions of the mask layer: when the average value of the critical dimensions of the edge area is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is a first pressure; when the average value of the critical dimensions of the edge area is less than the average value of the critical dimensions of the mask layer, the chamber pressure is a second pressure; the first pressure is less than the second pressure.

2. The method for pretreating a substrate according to claim 1, wherein: The first pressure is 15 mT to 50 mT.

3. The method for pretreating a substrate according to claim 1, wherein: The second pressure is 50 mT to 300 mT.

4. The method for pretreating a substrate according to claim 1, wherein: The pretreatment method further includes controlling the distribution of the process gas according to the critical dimension distribution of the mask layer.

5. The method for pretreating a substrate as claimed in claim 4, characterized in that: The process gas at least includes an etching gas, and the flow rate of the etching gas in each region of the mask layer is negatively correlated with the critical dimension of each region of the mask layer.

6. The method for pretreating a substrate as claimed in claim 5, characterized in that: The etching gas includes an oxidizing gas.

7. The method for pretreating a substrate according to claim 6, wherein: The oxidizing gas includes at least one of oxygen, ozone, nitrogen and nitrogen-containing oxygen gas.

8. The method for pretreating a substrate as claimed in claim 5, characterized in that: The total flow rate of the etching gas introduced into the plasma etching device is 200 sccm to 1500 sccm.

9. The method for pretreating a substrate according to claim 5, wherein: The process gas further includes a passivation gas, and the flow rate of the passivation gas in each region of the mask layer is positively correlated with the critical dimension of each region of the mask layer.

10. The substrate pretreatment method according to claim 9, characterized in that: The passivation gas includes at least one of a carbon fluorine gas and a carbon hydrogen fluorine gas.

11. The method for pretreating a substrate according to claim 10, wherein: The passivation gas includes at least one of CF4, C4F6, C4F8, CH2F2, and CHF3.

12. The substrate pretreatment method according to claim 9, characterized in that: The flow rate of the passivation gas in each area of ​​the mask layer is 0 sccm to 30 sccm.

13. The substrate pretreatment method according to claim 1, characterized in that: A protective layer is also arranged on the mask layer.

14. The method for pretreating a substrate according to claim 13, wherein: The protective layer is a residual anti-reflection layer.

15. The method for pretreating a substrate according to claim 14, wherein: The mask layer is a carbon-based mask, and the remaining anti-reflection layer is a non-carbon-based residual layer.

16. The substrate pretreatment method according to claim 1, characterized in that: The pre-processing method further includes adjusting at least one of a source radio frequency power, a bias radio frequency power and a pre-processing time of the plasma etching device according to a critical dimension of the mask layer.

17. The method for pretreating a substrate according to claim 16, wherein: The source radio frequency power is 500W to 1500W.

18. The method for pretreating a substrate according to claim 16, wherein: The pretreatment time is 15s to 120s.

19. The method for pretreating a substrate according to any one of claims 1 to 18, characterized in that: The edge area also includes an annular extreme edge area, the inner diameter of the annular extreme edge area is r2, the outer diameter is R, r2 / R≥0.98; wherein, the chamber pressure of the plasma etching device is controlled according to the distribution of the critical dimensions of the mask layer to be set as: when the average value of the critical dimensions of the extreme edge area is greater than the average value of the critical dimensions of the mask layer, the chamber pressure is a first pressure; when the average value of the critical dimensions of the extreme edge area is less than the average value of the critical dimensions of the mask layer, the chamber pressure is a second pressure; the first pressure is less than the second pressure.

20. A method for processing a substrate, characterized in that: include: Performing the substrate pretreatment method according to any one of claims 1 to 19 on the substrate; The pattern of the pre-treated mask layer is transferred to the substrate in the plasma etching device.

21. A plasma etching device, characterized in that: include: Reaction chamber; A base, which is arranged at the bottom of the reaction chamber and is used to carry a substrate with a radius of R; The substrate comprises a substrate and a mask layer to be processed on the substrate; the mask layer at least comprises an annular edge region, the inner diameter of the annular edge region is r, and r / R≥0.9; A gas supply component, the gas supply component at least comprising: a gas distributor and a gas shower head, the gas shower head is arranged at the top of the reaction chamber, opposite to the substrate; the gas shower head comprises a plurality of gas inlet channels, the gas shower head is divided into a plurality of regions in the radial direction, and the gas distributor is used to control the gas outlet flow rate of each region; Source RF source; Bias RF source; Extraction device; and A control unit, wherein the control unit controls the plasma etching device to execute the substrate processing method as claimed in claim 20.

22. The plasma etching device according to claim 21, characterized in that: The gas shower head is divided into a central area, a middle area and an edge area in the radial direction; or, the gas shower head is divided into a central area, a middle area, an edge area and an extreme edge area in the radial direction.

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