Wet etching method and wet etching device for metal silicide layer

Abstract

The present invention provides a wet etching method and wet etching device for a metal silicide layer. By irradiating the etching solution in an acid tank with light during the wet etching process of the metal silicide layer, the reaction of the product metal silicide layer in the etching solution can be catalyzed, thereby compensating for the etching rate reduced due to the increase in the use time of the etching solution. Furthermore, the intensity of the light is adjusted in real time according to the use time of the etching solution in the acid tank, and the etching rate of the product metal silicide layer can be adjusted in real time, thereby making the etching rate more stable, thereby solving the problem of unstable etching rate caused by the increase in the use time of the etching solution.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a wet etching method and a wet etching device for a metal silicide layer. Background Art

[0002] In the wet etching process of the metal silicide layer, since the product substrate in the wet etching process continuously reacts chemically with the etching solution in the acid tank, the concentration of the etching solution in the acid tank also decreases, which leads to the etching rate of the etching solution gradually decreasing with the increase of the use time. In order to ensure that the etching rate meets the process requirements, a predetermined program is usually set in the wet etching equipment, and the etching solution is replaced once after a predetermined working time according to the working time of the etching machine for wet etching, so as to ensure that the concentration of the etching solution in the acid tank is within a predetermined range. However, since the etching rate decreases with the increase of the use time of the etching solution in the acid tank, the problem of unstable etching rate will occur during the etching process. Summary of the invention

[0003] The object of the present invention is to provide a wet etching method and wet etching device for a metal silicide layer, so as to solve the problem of reduced etching rate and instability caused by increased use time of etching solution.

[0004] In order to solve the above technical problems, the present invention provides a wet etching method, comprising:

[0005] Providing a plurality of batches of product substrates, each batch of the product substrates having a product metal silicide layer formed thereon;

[0006] Sequentially wet-etching the metal silicide layers of multiple batches of products using the etching solution in the acid tank, and irradiating the etching solution in the acid tank with light during the wet etching process;

[0007] The intensity of the light is adjusted in real time according to the use time in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time.

[0008] Optionally, in the wet etching method of the metal silicide layer, the intensity of the light is adjusted in real time according to the following relationship so that the etching rate of the metal silicide layer of the product is within a predetermined etching rate:

[0009] Light=L 0 +C*lifetime;

[0010] Among them, Light represents the adjusted light intensity, L 0 It represents the initial light intensity of the etching solution, lifetime represents the usage time of the etching solution in the acid tank; C represents the correlation coefficient between the light intensity and the usage time of the etching solution.

[0011] Optionally, in the wet etching method of the metal silicide layer, before sequentially wet etching the metal silicide layers of the multiple batches of products using the etching solution in the acid tank, the wet etching method of the metal silicide layer further includes:

[0012] The etching solution in the acid tank is illuminated by using the initial illumination intensity, and the etching rate of the etching solution in the acid tank at the initial time is collected to obtain the initial etching rate of the etching solution in the acid tank;

[0013] Collecting the etching rate of the etching solution in the acid tank during the preset use time, and adjusting the intensity of the light according to the etching rate of the etching solution during the preset use time, so that the real-time etching rate of the etching solution is the same as the initial etching rate; and,

[0014] According to the adjusted intensity of the light and the predetermined use time, a correlation coefficient between the intensity of the light and the use time of the etching solution is obtained.

[0015] Optionally, in the wet etching method of the metal silicide layer, when the metal silicide layers of the multiple batches of products are wet-etched in sequence using the etching solution in the acid tank, a portion of the thickness of the metal silicide layer is removed.

[0016] Optionally, in the wet etching method of the metal silicide layer, the wet etching method of the metal silicide layer further comprises:

[0017] The usage time of the etching solution in the acid tank is compared with a preset threshold, and whether the usage time is greater than or equal to the preset threshold is determined based on the comparison result. If so, the etching solution in the acid tank is replaced, and the replaced etching solution is used to wet-etch the metal silicide layer.

[0018] Optionally, in the wet etching method of the metal silicide layer, the use time of the etching solution in the acid tank is the time the etching solution is placed in the acid tank.

[0019] Optionally, in the wet etching method of the metal silicide layer, the light source used for the illumination is white light with a wavelength of 390nm to 778nm.

[0020] Optionally, in the wet etching method of the metal silicide layer, the etching solution in the acid tank includes ammonia water, hydrogen peroxide and deionized water.

[0021] Based on the same inventive concept, the present invention provides a wet etching device, the wet etching device comprising:

[0022] An acid tank for containing an etching solution and a plurality of batches of product substrates, on which a product metal silicide layer is formed, so as to sequentially wet-etch the plurality of batches of product metal silicide layers using the etching solution in the acid tank;

[0023] An illumination module, used for irradiating the etching solution in the acid tank with light during the wet etching process;

[0024] The control module is connected to the illumination module and is used to adjust the intensity of the illumination in real time according to the use time of the etching solution in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time.

[0025] Optionally, in the wet etching device, the wet etching device also includes an acquisition module and a comparison module, the acquisition module is used to acquire the usage time of the etching solution in the acid tank and provide the usage time to the comparison module, the comparison module is used to compare the usage time with a preset threshold value, and when the comparison result is that the usage time is greater than or equal to the preset threshold value, a trigger signal is sent to the control module, and the control module replaces the etching solution in the acid tank according to the trigger signal.

[0026] In the wet etching method and wet etching device of the metal silicide layer provided by the present invention, by irradiating the etching solution in the acid tank with light during the wet etching process, the reaction between the etching solution in the acid tank and the product metal silicide layer can be photocatalyzed, thereby increasing the etching rate of the product metal silicide layer, thereby compensating for the etching rate reduced due to the increase in the use time of the etching solution. Furthermore, the intensity of the illumination is adjusted in real time according to the use time of the etching solution in the acid tank, and the etching rate of the product metal silicide layer can be adjusted in real time, thereby maintaining the etching rate in a stable state, thereby solving the problem of unstable etching rate caused by the increase in the use time of the etching solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic flow chart of a wet etching method for a metal silicide layer according to an embodiment of the present invention;

[0028] Figure 2 is a schematic cross-sectional view of a metal silicide layer in a wet etching method for a metal silicide layer according to an embodiment of the present invention;

[0029] Figure 3 is a curve diagram showing the relationship between the etching rate and the use time of the etching solution in the acid tank in the wet etching method of the metal silicide layer according to the embodiment of the present invention;

[0030] Figure 4 is a curve diagram showing the relationship between the intensity of light and the use time of the etching solution in the acid tank in the wet etching method of the metal silicide layer according to the embodiment of the present invention;

[0031] Figure 5 is a schematic diagram of the principle of a wet etching device according to an embodiment of the present invention;

[0032] The reference numerals are described as follows:

[0033] 100-product substrate; 110-gate structure; 120-metal silicide layer;

[0034] 201-acid tank; 202-illumination module; 203-comparison module; 204-control module; 205-acquisition module. DETAILED DESCRIPTION

[0035] The wet etching method and wet etching device of the metal silicide layer proposed by the present invention are further described in detail below in combination with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0036] Figure 1 FIG. 1 is a schematic diagram of a wet etching method for a metal silicide layer provided by the present invention. Figure 1 As shown, the wet etching method of the metal silicide layer includes:

[0037] Step S1: providing a plurality of batches of product substrates, each batch of the product substrates having a product metal silicide layer formed thereon;

[0038] Step S2: using the etching solution in the acid tank to sequentially wet-etch the metal silicide layers of the multiple batches of products, and irradiating the etching solution in the acid tank with light during the wet etching process; and

[0039] Step S3: adjusting the intensity of the light in real time according to the use time of the etching solution in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time.

[0040] Figure 2 is a schematic cross-sectional view of a metal silicide layer in a wet etching method according to an embodiment of the present invention; Figure 3 is a curve diagram showing the relationship between the etching rate and the use time of the etching solution in the acid tank in the wet etching method according to an embodiment of the present invention; Figure 4 FIG. 1 is a graph showing the relationship between the intensity of light and the use time of the etching solution in the acid tank in the wet etching method according to an embodiment of the present invention; Figure 2 to Figure 4 The wet etching method provided in this embodiment is introduced in more detail.

[0041] refer to Figure 2, perform step S1, provide multiple batches of product substrates 100, each batch of the product substrates 100 has a product metal silicide layer 120 formed thereon; the specifications (film thickness, material, size, etc.) of the multiple batches of product substrates 100 are the same, and the specifications of the multiple batches of product metal silicide layers are the same. Each batch may include multiple product substrates, each product substrate 100 has a product metal silicide layer 120 formed thereon. In addition, a gate structure 110 is also formed on the product substrate 100, and the product metal silicide layer 120 covers the top surface of the gate structure 110 and the product substrate 100.

[0042] The product substrate 100 may be a silicon product substrate, a germanium product substrate, a germanium silicon product substrate, a gallium arsenide product substrate or a silicon-on-insulator product substrate, etc. A plurality of source regions S and a plurality of drain regions D may be formed in the product substrate 100, the source regions S and the drain regions D are arranged at intervals, and a trench isolation structure (not shown) for isolating the active regions S is also formed in the product substrate 100, etc., which is not limited by the present invention. A plurality of discrete gate structures 110 are formed on the product substrate 100, and each of the gate structures 110 is located on the product substrate 100 between the source region S and the drain region D.

[0043] like Figure 2 As shown, a product metal silicide layer 120 is formed on the top surface of the gate structure 110 and the source region S and the drain region D (i.e., the surface of a portion of the product substrate 100 ), that is, the product metal silicide layer 120 covers the top surface of the gate structure 110 and the substrate 100 .

[0044] In this embodiment, the material of the product metal silicide layer 120 can be cobalt silicide (CoSi2). In other embodiments, the material of the product metal silicide layer 120 can also be one or more of titanium silicide (TiSi2), nickel silicide (NiSi2), molybdenum silicide (MoSi2), platinum silicide (PtSi2), tantalum silicide (TaSi2), tungsten silicide (WSi2), etc.

[0045] In this embodiment, the steps of forming the product metal silicide layer 120 include: first, depositing a metal cobalt layer (not shown) and a titanium nitride layer (not shown) covering the metal cobalt layer on the entire product substrate 100, and then performing a high-temperature annealing treatment (500°C~750°C) to allow the metal cobalt layer to react with the silicon in the product substrate 100 to generate a product metal silicide layer 120 at the contact surface between the metal cobalt layer and the product substrate 100.

[0046] Next, step S2 is performed to sequentially wet-etch the metal silicide layers of the products in the plurality of batches using the etching solution in the acid tank, and irradiate the etching solution during the wet etching process with light. Irradiation with light can photocatalyze the reaction between the etching solution and the metal silicide layer of the product, thereby accelerating the etching rate of the metal silicide layer of the product.

[0047] In this embodiment, the acid tank can be a well-known etching acid tank, which is used to contain an etching solution. The etching solution in the acid tank can be used to etch the product metal silicide layer, so the etching solution in the acid tank can include ammonia (NH4OH), hydrogen peroxide (H2O2) and deionized water. By wet etching the product metal silicide layer, a partial thickness of the product metal silicide layer 120 can be removed, and the unreacted metal cobalt layer in the product metal silicide layer (the metal cobalt layer in the formation process of the product metal silicide layer 120) can be removed.

[0048] like Figure 3 As shown, as the use time of the etching solution in the acid tank increases, the etching rate will decrease accordingly. Based on this, in the present embodiment, during the wet etching process, the etching solution in the wet etching process is illuminated, and the illumination can photocatalyze the reaction between the etching solution and the metal silicide layer of the product to increase the etching rate of the metal silicide layer of the product, thereby compensating for the etching rate reduced due to the increase in the use time of the etching solution. Wherein, the use time in the acid tank refers to the time that the etching solution is placed in the acid tank. The inventor has found that during the use of the etching solution, due to the influence of factors such as the volatilization of the acid solution, the etching rate will decrease in a linear relationship with the increase in the time that the etching solution is placed in the acid tank. Therefore, in the present embodiment, the etching solution in the acid tank is replaced in time by monitoring the time that the etching solution is placed in the acid tank to further stabilize the etching rate.

[0049] In a preferred embodiment, when the etching solution in the acid tank is illuminated during the wet etching process, the light source used is white light, and a lighting module can be used to provide illumination, and the lighting module can be, for example, an incandescent lamp, an LED, etc. The lighting module can be arranged perpendicular to the acid tank, and the lighting module can be arranged, for example, directly above the acid tank so that the illumination of the etching solution in the acid tank is more uniform. Further, during the wet etching process, the lighting module used to provide illumination is fixed, for example, it can be fixed above the acid tank by a bracket to avoid the lighting module shaking during the wet etching process and affecting the intensity of the illumination, thereby avoiding affecting the stability of the etching rate. In this embodiment, the illumination wavelength can be 390nm to 778nm, so as to promote or accelerate the etching reaction process, thereby increasing the etching rate of the metal silicide layer of the product.

[0050] Next, step S3 is performed to adjust the intensity of the light in real time according to the use time of the etching solution in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time, thereby maintaining the stability of the etching rate of the metal silicide layer of the product by the etching solution in the acid tank. Figure 3 Shown, along with the increase of the service life of the etching solution (ammonia and / or hydrogen peroxide) in the acid tank, the etching rate can decline accordingly, and the stronger the illumination is, the stronger the catalytic ability of the etching solution is, and then the etching rate of the product metal silicide layer is accelerated, therefore, in the present embodiment, according to the intensity of the service life in the acid tank, the illumination is adjusted in real time, the etching rate can be adjusted in real time, thereby the etching rate that reduces because of the increase of the service life of the etching solution can be effectively compensated. In other embodiments, when regulating the intensity of illumination, the wavelength of illumination can also be adjusted, thereby further increasing the etching rate of the etching solution, accelerating etching, thereby saving process time.

[0051] Specifically, the intensity of the light can be adjusted according to the following relationship: Light = L 0 +C*lifetime; where Light represents the adjusted light intensity, L 0 represents the initial light intensity of the etching solution, lifetime represents the usage time of the etching solution in the acid tank; C represents the correlation coefficient between the light intensity and the usage time of the etching solution in the acid tank.

[0052] Among them, the method for obtaining the correlation coefficient between the intensity of the light and the use time of the etching solution includes: first, providing multiple batches of test substrates, each batch of the test substrates has a test product metal silicide layer formed on it, and the material of the test metal silicide layer is the same as the material of the product metal silicide layer.

[0053] Then, the etching solution in the acid tank is used to sequentially perform wet etching on multiple batches of test metal silicide layers. During the wet etching process, the etching solution in the acid tank is illuminated by an initial light intensity, and the etching rate of the etching solution in the acid tank at the initial time is collected to obtain the initial etching rate of the etching solution in the acid tank. Before sequentially performing wet etching on multiple batches of test metal silicide layers using the etching solution in the acid tank, the etching solution in the acid tank is replaced with a new one to ensure the accuracy of the collected data.

[0054] Next, the etching rate of the etching solution in the acid tank during the preset use time is collected, and the intensity of the light is adjusted according to the etching rate of the etching solution during the preset use time, so that the real-time etching rate of the etching solution is the same as the initial etching rate. Figure 4As shown, for example, after the use time reaches T1, T2, T3, the light intensity L1, L2, L3 required for the etching rate of the test metal silicide layer to reach the initial etching rate can be collected; and according to the adjusted light intensity and the predetermined use time, the correlation coefficient between the light intensity and the use time of the etching solution is obtained. In a preferred embodiment of the present invention, the functional relationship can be plotted as follows Figure 4 The curve of the intensity of light and the use time of the etching solution is fitted to obtain the correlation coefficient C between the intensity of light and the use time of the etching solution.

[0055] In this embodiment, the method for wet etching of the metal silicide layer further comprises: comparing the use time of the etching solution in the acid tank with a preset threshold value, and judging whether the use time is greater than or equal to the preset threshold value, and if so, replacing the etching solution in the acid tank, and wet etching the metal silicide layer of the product with the replaced etching solution. Wherein, the preset threshold value can be, for example, 24 hours. Thus, the etching solution in the acid tank is monitored, so that the etching solution in the acid tank is replaced in time.

[0056] Figure 5 Schematic diagram of the principle of the wet etching device of the embodiment of the present invention. Based on the same inventive concept, the present invention also provides a wet etching device, such as Figure 5 As shown, the wet etching device includes an acid tank 201 , a light module 202 , and a control module 204 .

[0057] The acid tank 201 is used to accommodate etching solution and multiple batches of product substrates, on which product metal silicide layers are formed, so that the etching solution in the acid tank 201 is used to sequentially perform wet etching on multiple batches of product metal silicide layers; the light irradiation module 202 is used to illuminate the etching solution in the acid tank 201 during the wet etching process, wherein the light irradiation module 202 can be arranged directly above the acid tank 201, for example, can be fixed directly above the acid tank 201 by a bracket, so that the light emitted by the light irradiation module 202 can be uniformly irradiated on the etching solution in the acid tank 201. The light irradiation module 202 can be fixed directly above the acid tank 201 by a bracket. The control module 204 is connected to the light irradiation module 202, and is used to adjust the intensity of the light in real time according to the use time of the etching solution in the acid tank 201, so as to adjust the etching rate of the product metal silicide layer in real time.

[0058] In this embodiment, the wet etching device also includes an acquisition module 205 and a comparison module 203. The acquisition module 205 is used to obtain the usage time of the etching solution in the acid tank 201 and provide the usage time to the comparison module 203. The comparison module 203 is used to compare the usage time with a preset threshold value, and when the comparison result is that the usage time is greater than or equal to the preset threshold value, a trigger signal is sent to the control module 204. The control module 204 replaces the etching solution in the acid tank 201 according to the trigger signal.

[0059] In summary, in the wet etching method and wet etching device provided by the present invention, by irradiating the etching solution in the acid tank during the wet etching process, the irradiation can photocatalyze the reaction between the etching solution and the product metal silicide layer, thereby increasing the etching rate of the product metal silicide layer, thereby compensating for the etching rate that decreases due to the increase in the use time of the etching solution. Furthermore, the intensity of the irradiation can be adjusted in real time according to the use time of the etching solution in the acid tank, and the etching rate of the product metal silicide layer can be adjusted in real time, thereby making the etching rate more stable, thereby solving the problem of unstable etching rate caused by the increase in the use time of the etching solution.

[0060] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A wet etching method for a metal silicide layer, It is characterized in that The wet etching method of the metal silicide layer comprises: Providing a plurality of batches of product substrates, each batch of the product substrates having a product metal silicide layer formed thereon; Sequentially wet-etching the metal silicide layers of multiple batches of products using the etching solution in the acid tank, and irradiating the etching solution in the acid tank with light during the wet etching process; The intensity of the light is adjusted in real time according to the use time of the etching solution in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time, wherein the etching rate of the metal silicide layer of the product is increased by increasing the intensity of the light to compensate for the etching rate of the metal silicide layer of the product which is reduced due to the increase in the use time of the etching solution.

2. The wet etching method for the metal silicide layer according to claim 1, It is characterized in that The intensity of the light is adjusted in real time according to the following relationship so that the etching rate of the metal silicide layer of the product is within a predetermined etching rate: Light=L 0 +C*lifetime; Among them, Light represents the adjusted light intensity, L 0 represents the initial light intensity of the etching solution, lifetime represents the usage time of the etching solution in the acid tank; C represents the correlation coefficient between the light intensity and the usage time of the etching solution in the acid tank.

3. The wet etching method of the metal silicide layer according to claim 2, It is characterized in that The method for obtaining the correlation coefficient between the intensity of the light and the use time of the etching solution in the acid tank comprises: Providing multiple batches of test substrates, each batch of the test substrates having a test product metal silicide layer formed thereon, the material of the test product metal silicide layer being the same as the material of the product metal silicide layer; Sequentially wet-etching a plurality of batches of test metal silicide layers using the etching solution in the acid tank, and during the wet etching process, irradiating the etching solution in the acid tank with an initial light intensity, and collecting the etching rate of the etching solution in the acid tank at the initial time to obtain the initial etching rate of the etching solution in the acid tank; Collecting the etching rate of the etching solution in the acid tank during the preset use time, and adjusting the intensity of the light according to the etching rate of the etching solution during the preset use time, so that the real-time etching rate of the etching solution is the same as the initial etching rate; and, According to the adjusted intensity of the light and the preset use time, a correlation coefficient between the intensity of the light and the use time of the etching solution is obtained.

4. The wet etching method of the metal silicide layer according to claim 1, It is characterized in that When the multiple batches of product metal silicide layers are wet-etched in sequence using the etching solution in the acid tank, a portion of the thickness of the product metal silicide layer is removed.

5. The wet etching method of the metal silicide layer according to claim 1, It is characterized in that The method for wet etching the metal silicide layer further comprises: The usage time of the etching solution in the acid tank is compared with a preset threshold, and whether the usage time is greater than or equal to the preset threshold is determined based on the comparison result. If so, the etching solution in the acid tank is replaced, and the replaced etching solution is used to wet-etch the metal silicide layer of the product.

6. The wet etching method of the metal silicide layer according to claim 1, It is characterized in that The use time of the etching solution in the acid tank is the time the etching solution is placed in the acid tank.

7. The wet etching method for the metal silicide layer according to claim 1, It is characterized in that The light source used for the illumination is white light with a wavelength of 390nm to 778nm.

8. The wet etching method for a metal silicide layer according to claim 1, It is characterized in that The etching solution in the acid tank includes ammonia water, hydrogen peroxide and deionized water.

9. A wet etching device, It is characterized in that The wet etching device comprises: An acid tank for containing an etching solution and a plurality of batches of product substrates, on which a product metal silicide layer is formed, so as to sequentially wet-etch the plurality of batches of product metal silicide layers using the etching solution in the acid tank; An illumination module, used for irradiating the etching solution in the acid tank with light during the wet etching process; A control module is connected to the illumination module and is used to adjust the intensity of the illumination in real time according to the use time of the etching solution in the acid tank, so as to adjust the etching rate of the metal silicide layer of the product in real time, wherein the etching rate of the metal silicide layer of the product is increased by increasing the intensity of the illumination to compensate for the etching rate of the metal silicide layer of the product which is reduced due to the increase in the use time of the etching solution.

10. The wet etching device according to claim 9, It is characterized in that The wet etching device also includes an acquisition module and a comparison module. The acquisition module is used to acquire the usage time of the etching solution in the acid tank and provide the usage time to the comparison module. The comparison module is used to compare the usage time with a preset threshold value, and when the comparison result is that the usage time is greater than or equal to the preset threshold value, a trigger signal is sent to the control module. The control module replaces the etching solution in the acid tank according to the trigger signal.

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