Cleaning method after etching

Abstract

The invention discloses a cleaning method after etching, which comprises the following steps: a substrate is provided, a region for forming a semiconductor device on the substrate comprises a first region and a second region, a PMOS (P-channel Metal Oxide Semiconductor) device is formed in the first region, the second region is used for forming an NMOS (N-channel Metal Oxide Semiconductor) device, and the PMOS device comprises a first metal gate and work function layers on the peripheral side and the bottom of the first metal gate; the pseudo gate in the second region is etched to form a groove; spraying ammonia water on the substrate for cleaning; and spraying isopropanol on the substrate to remove residual ammonia water. In the manufacturing process of the HKMG device, after the PMOS device is formed, the pseudo gate in the area where the NMOS device is located is etched and then cleaned, the oxidation layer on the surface of the device is cleaned by spraying the ammonia water, and the residual ammonia water is removed by spraying the isopropanol, so that the yield of the HKMG device is improved. Therefore, the residual ammonia water is prevented from entering the metal gate through the weak area of the side wall of the PMOS device to corrode the metal gate, and the reliability and yield of the device are improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices and integrated circuits, and in particular to a post-etching cleaning method used in the manufacturing process of HKMG devices. Background Art

[0002] In the semiconductor integrated circuit manufacturing industry, compared with polysilicon gate (poly gate), metal gate (MG) has a lower resistivity, which can improve carrier mobility and threshold voltage (V T ) regulation capability; at the same time, since high dielectric constant (high-k) insulating materials can increase capacitance and improve the gate's control over the device, they can replace the traditional silicon dioxide (SiO2) gate dielectric layer in the device structure with a metal gate, making high dielectric constant metal gate (high-k metal gate, HKMG) devices widely used.

[0003] In the related art, the manufacturing process of HKMG devices usually adopts the process of first manufacturing P (postive) type metal-oxide-semiconductor field-effect transistor (MOSFET, hereinafter referred to as "MOS") devices, and then manufacturing N-type MOS devices. Separate manufacturing can separately regulate NMOS devices and PMOS devices, thereby improving the performance of the devices. In the process of separately filling the work function layer, compared with the traditional polysilicon gate manufacturing process, a polysilicon (dummy gate) removal process is added.

[0004] Generally, in the process of making NMOS devices after the PMOS devices are made, after the polysilicon is removed, two steps are performed for cleaning: the first step is to remove the organic polymer after dry etching by N-methylpyrrolidone (NMP), and the second step is to remove the oxide layer on the surface of titanium nitride (TiN) on the NMOS by ammonia to reduce the threshold voltage. However, the sidewall between the NMOS device and the PMOS device usually has a weak point, which is difficult to withstand the ammonia process, resulting in damage to the metal gate and surface roughness defects, thereby reducing the reliability and yield of the product. Summary of the invention

[0005] The present application provides a post-etching cleaning method, which can solve the problem that the metal gate of the NMOS device is easily damaged by cleaning after etching the dummy gate of the PMOS device in the manufacturing process of the HKMG device provided in the related art. The method comprises:

[0006] A substrate is provided, wherein an area on the substrate for forming a semiconductor device comprises a first area and a second area, wherein a PMOS device is formed in the first area, and the second area is used to form an NMOS device, wherein the PMOS device comprises a first metal gate and a work function layer around and at the bottom of the first metal gate, and a dummy gate in the second area is etched to form a groove;

[0007] spraying ammonia water on the substrate for cleaning;

[0008] The substrate was sprayed with isopropyl alcohol to remove residual ammonia.

[0009] In some embodiments, the first metal gate comprises metal aluminum.

[0010] In some embodiments, the time for spraying isopropyl alcohol on the substrate to remove residual ammonia is 15 seconds to 60 seconds.

[0011] In some embodiments, during the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, the flow rate of the isopropyl alcohol is 50 ml to 500 ml.

[0012] In some embodiments, during the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, the temperature of the isopropyl alcohol is 20 degrees Celsius to 70 degrees Celsius.

[0013] In some embodiments, in the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, deionized water is sprayed by a nano-atomization process.

[0014] In some embodiments, the flow rate of deionized water in the nano-scale atomization process is 80 ml to 125 ml.

[0015] In some embodiments, spraying ammonia water on the substrate for cleaning includes:

[0016] Ammonia water is sprayed on the substrate, and the substrate is cleaned by centrifugal drying.

[0017] The technical solution of this application has at least the following advantages:

[0018] In the manufacturing process of the HKMG device, after forming the PMOS device, the dummy gate in the area where the NMOS device is located is etched, the oxide layer on the surface of the device is cleaned by spraying ammonia water, and the residual ammonia water is removed by spraying isopropyl alcohol, thereby preventing the residual ammonia water from entering the metal gate through the weak area of ​​the side wall of the PMOS device to corrode it, thereby solving the problem of surface roughness of the metal gate of the PMOS device caused by damage to a certain extent, and improving the reliability and yield of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 is a flow chart of a cleaning method provided by an exemplary embodiment of the present application;

[0021] Figure 2 It is a schematic cross-sectional view of the dummy gate of the NMOS region after etching. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] In the description of the present application, it should be noted that the terms "center", "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 application 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 application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0024] In the description of this application, 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 or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0026] refer to Figure 1, which shows a flow chart of a cleaning method provided by an exemplary embodiment of the present application, the method is applied in the manufacturing process of HKMG devices, such as Figure 1 As shown, the method includes:

[0027] Step S1, providing a substrate, the area on the substrate for forming a semiconductor device includes a first area and a second area, a PMOS device is formed in the first area, the second area is used to form an NMOS device, the PMOS device includes a first metal gate and a work function layer around and at the bottom of the first metal gate, and a dummy gate in the second area is etched to form a groove.

[0028] Step S2, spraying ammonia water on the substrate for cleaning.

[0029] For example, the substrate may be sprayed with ammonia water and cleaned by centrifugal drying to clean the byproducts of dry etching and to clean off some oxide layers on the surface below the NMOS device. Figure 2 As shown, the area on the substrate for forming a semiconductor device includes a first area 201 and a second area 202, a PMOS device is formed in the first area 201, and the second area 202 is used to form an NMOS device, the PMOS device includes a first metal gate 231 and a work function layer around and at the bottom of the first metal gate, a dummy gate of the second area 202 is etched to form a groove 301, and a hard mask (HM) layer (including a titanium nitride (TiN) layer 261 and a silicon dioxide (SiO2) layer 262 from bottom to top) is left above the PMOS device in the first area 201 after etching, and the first metal gate 231 may include metal aluminum (Al).

[0030] The work function layer includes a tantalum nitride (TaN) layer 221, a titanium nitride layer 222, a tantalum nitride layer 223 and a titanium nitride layer 224 from the inside to the outside; a shallow trench isolation (STI) is formed in the substrate of the first region 201 and the second region 202. A trench isolation (STI) structure 212 is provided, and an interface layer 211, a high dielectric constant layer (composed of a material with a dielectric constant k greater than 10) 212 and a cap layer 213 are sequentially formed between the work function layer and the substrate from bottom to top. The high dielectric constant layer 212 may include at least one of hafnium oxide (HfO2), tantalum oxide (Ta2O5), strontium titanium oxide (SrTiO3), hafnium silicon oxide (HfSiO), and zirconium oxide (ZrO2). The interface layer 211 may include an oxide layer (for example, a silicon dioxide (SiO2) layer may be formed on the substrate 210 by a thermal oxidation process), and the cap layer 213 may include a nitride layer (for example, a titanium nitride layer, a silicon nitride (Si3N4) layer, or a tantalum nitride layer); a P-type pull-up tube (positive type pull-up, PPU) 2011 is formed in the substrate of the first region 201, and an N-type pull-down tube (negative type pull-up, PPU) 2011 is formed in the substrate of the second region 202. pull-down, NPD)2012.

[0031] After etching, the hard mask layer is difficult to completely cover the sidewalls of the work function layer, so the boundary area between the first region 201 and the second region 202 (eg Figure 2 The area indicated by the dotted ellipse in the middle is relatively weak. When the substrate is sprayed with ammonia water, the ammonia water enters from the weak area of ​​the side wall of the work function layer and reacts with the metal aluminum in the first metal gate 231 to generate aluminum hydroxide (Al(OH)3), which remains on the surface of the first metal gate 231, causing rough defects on the surface. In view of this, the substrate can be sprayed with ammonia water in a step-by-step manner (i.e., by using a multiple-spraying manner) to reduce the residual ammonia water.

[0032] Step S3, spraying isopropyl alcohol on the substrate to remove residual ammonia.

[0033] Optionally, in step S3, the time for spraying isopropyl alcohol (IPA) on the substrate to remove residual ammonia is 15 seconds (s) to 60 seconds; in the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, the flow rate of isopropyl alcohol is 50 milliliters (mL) to 500 milliliters; in the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, the temperature of the isopropyl alcohol is 20 degrees Celsius (℃) to 70 degrees Celsius.

[0034] Exemplarily, in the process of spraying isopropyl alcohol on the substrate to remove residual ammonia, deionized water can also be sprayed on the substrate through a nano-spray process to remove residual ammonia (i.e., residual ammonia is removed by spraying IPA + nano-sprayed deionized water), and the flow rate of deionized water in the nano-spray process is 80 ml to 125 ml.

[0035] In summary, in the embodiment of the present application, in the manufacturing process of the HKMG device, after the PMOS device is formed, the dummy gate in the area where the NMOS device is located is etched, the oxide layer on the surface of the device is cleaned by spraying ammonia water, and the residual ammonia water is removed by spraying isopropyl alcohol, thereby preventing the residual ammonia water from entering the metal gate through the weak area of ​​the side wall of the PMOS device to corrode it, thereby solving the problem of surface roughness of the metal gate of the PMOS device due to damage to a certain extent, and improving the reliability and yield of the device.

[0036] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A cleaning method after etching, characterized in that: The method is applied to the manufacturing process of the HKMG device, and the method comprises: A substrate is provided, wherein an area on the substrate for forming a semiconductor device comprises a first area and a second area, wherein a PMOS device is formed in the first area, and the second area is used to form an NMOS device, wherein the PMOS device comprises a first metal gate and a work function layer around and at the bottom of the first metal gate, and a dummy gate in the second area is etched to form a groove; spraying ammonia water on the substrate for cleaning; The substrate was sprayed with isopropyl alcohol to remove residual ammonia.

2. The method according to claim 1, characterized in that The first metal gate includes metal aluminum.

3. The method according to claim 2, characterized in that The time for spraying isopropyl alcohol on the substrate to remove residual ammonia water is 15 seconds to 60 seconds.

4. The method according to claim 3, characterized in that In the process of spraying isopropyl alcohol on the substrate to remove residual ammonia water, the flow rate of the isopropyl alcohol is 50 ml to 500 ml.

5. The method according to claim 4, characterized in that In the process of spraying isopropyl alcohol on the substrate to remove residual ammonia water, the temperature of the isopropyl alcohol is 20 degrees Celsius to 70 degrees Celsius.

6. The method according to claim 5, characterized in that In the process of spraying isopropyl alcohol on the substrate to remove residual ammonia water, deionized water is also sprayed through a nano-scale atomization process.

7. The method according to claim 6, characterized in that The flow rate of deionized water in the nano-scale atomization process is 80 ml to 125 ml.

8. The method according to any one of claims 1 to 7, characterized in that: The step of spraying ammonia water on the substrate for cleaning comprises: Ammonia water is sprayed on the substrate, and the substrate is cleaned by centrifugal drying.

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