Phase change temperature monitoring method

Abstract

The present application discloses a method for monitoring the phase change temperature used in a nickel silicon layer preparation process, comprising: obtaining a first resistance value, the first resistance value being the square resistance of a first thin film layer when heat treated at a first preset temperature, the first thin film layer being formed on a first substrate, the first thin film layer comprising a titanium nitride layer and a titanium layer, and the first substrate comprising silicon; obtaining a second resistance value, the second resistance value being the square resistance of a second thin film layer when heat treated at a second preset temperature, the second thin film layer being formed on a second substrate, the second thin film layer comprising a titanium nitride layer and a titanium layer, and the second substrate comprising silicon, the first preset temperature and the second preset temperature being unequal; and monitoring the temperature of the heat treatment based on the difference between the first resistance value and the second resistance value. The present application improves the accuracy of phase change temperature monitoring by obtaining the square resistance of thin film layers at different preset temperatures and monitoring the temperature of the heat treatment based on the difference in square resistance.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a method for monitoring phase change temperature used in a nickel silicon (NiSi) layer preparation process. Background Art

[0002] In chip manufacturing, the nickel silicon layer serves as a dielectric layer between the silicon substrate and the metal layer. The completeness of the phase change reaction during its formation will directly affect the electrical performance of the chip.

[0003] Typically, a nickel silicon layer is formed by sequentially growing a titanium nitride (TiN) layer and a titanium (Ti) layer on a silicon substrate, and then undergoing a two-step phase change reaction. The phase change steps include: in the first step, silicon, nickel, and titanium are transformed into Ni2Si at a first temperature (usually around 300 degrees Celsius); in the second step, Ni2Si is transformed into NiSi at a second temperature (around 410 degrees Celsius). The core of the preparation process is to be able to stably transform into Ni2Si in the first step. However, the temperature range that can ensure the stability of the first phase change is relatively small, so effectively monitoring the phase change temperature is particularly important for process control.

[0004] In the related art, a method for monitoring the phase transition temperature in the nickel silicon layer preparation process includes: growing a thin film layer on a wafer, the thin film layer including a titanium nitride layer and a titanium layer from bottom to top, performing a heat treatment at a preset temperature, and obtaining the sheet resistance (R S ), if the change value of the square resistance is within the preset change range, it is determined that the heat treatment temperature of the equipment meets the requirements.

[0005] However, the square resistance of the thin film layer is not sensitive to small temperature fluctuations, but small temperature fluctuations will have a greater impact on the phase change of the thin film layer. Therefore, the sensitivity and accuracy of monitoring the phase change temperature through the square resistance of the thin film layer are low. Summary of the Invention

[0006] The present application provides a method for monitoring phase change temperature, which can solve the problem of low sensitivity and accuracy of the phase change temperature monitoring method provided in the related art.

[0007] On the one hand, an embodiment of the present application provides a method for monitoring phase transition temperature, which is applied to a process for preparing a nickel silicon layer, and the method includes:

[0008] Obtaining a first resistance value, where the first resistance value is a sheet resistance of a first thin film layer when heat treated at a first preset temperature, the first thin film layer being formed on a first substrate, the first thin film layer including a titanium nitride layer and a titanium layer, and the first substrate including silicon;

[0009] Obtaining a second resistance value, where the second resistance value is a square resistance of the second thin film layer when the heat treatment is performed at a second preset temperature, the second thin film layer being formed on a second substrate, the second thin film layer including a titanium nitride layer and a titanium layer, the second substrate including silicon, and the first preset temperature and the second preset temperature being unequal;

[0010] The temperature of the heat treatment is monitored according to the difference between the first resistance value and the second resistance value.

[0011] Optionally, monitoring the temperature of the heat treatment according to the difference between the first resistance value and the second resistance value includes:

[0012] If the difference changes from high to low, it is determined that the temperature of the heat treatment is lower than the preset temperature.

[0013] Optionally, monitoring the temperature according to a difference between the first sheet resistance and the second sheet resistance includes:

[0014] If the difference changes from low to high, it is determined that the temperature of the heat treatment is higher than the preset temperature.

[0015] Optionally, obtaining the first resistance value includes:

[0016] placing the first substrate having the first thin film layer formed thereon in a heat treatment device, wherein the temperature of the heat treatment device is set to the first preset temperature;

[0017] Performing heat treatment at the first preset temperature;

[0018] The sheet resistance of the first thin film layer is obtained at every preset time interval to obtain the first resistance value.

[0019] Optionally, obtaining the second resistance value includes:

[0020] placing the second substrate having the second thin film layer formed thereon in the heat treatment equipment, wherein the temperature of the heat treatment equipment is set to the second preset temperature;

[0021] performing heat treatment at the second preset temperature;

[0022] The sheet resistance of the second thin film layer is acquired at each preset time interval to obtain the second resistance value.

[0023] Optionally, the first preset temperature is greater than 290 degrees Celsius and less than 300 degrees Celsius.

[0024] Optionally, the second preset temperature is greater than 295 degrees Celsius and less than 310 degrees Celsius.

[0025] The technical solution of this application has at least the following advantages:

[0026] By heat-treating a substrate formed with a titanium nitride layer / titanium layer at different preset temperatures, the square resistance of the thin film layer at different preset temperatures is obtained, and the temperature of the heat treatment is monitored according to the difference in the square resistance of the thin film layer at different preset temperatures. Since the difference in the square resistance at different preset temperatures is related to the temperature drift and is easy to detect, the problem of low monitoring sensitivity and accuracy caused by monitoring the phase change temperature based on the square resistance at a single monitoring temperature in the related technology is solved because the square resistance is not sensitive to small temperature fluctuations, thereby improving the accuracy of phase change temperature monitoring, thereby improving the stability of the process and the yield of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. 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 any creative work.

[0028] Figure 1 It is the phase transition curve of Ni2Si;

[0029] Figure 2 is a flow chart of a method for monitoring phase change temperature provided by an exemplary embodiment of the present application;

[0030] Figure 3 This is a schematic diagram showing how the temperature offset varies with the difference in sheet resistance. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in this application in conjunction with the accompanying drawings. Obviously, the embodiments described 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 making any creative efforts are within the scope of protection of this application.

[0032] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connections between two components; they can refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0034] 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.

[0035] refer to Figure 1 , which shows the phase transition curve of Ni2Si, such as Figure 1 As shown, the horizontal axis is the temperature of the film layer (titanium nitride layer and titanium layer), and the vertical axis is the square resistance of the film layer. Figure 1 The position indicated by the circle in the middle, for example, may be 300 degrees Celsius) undergoes phase change, however, near the monitoring point (such as Figure 1 The range indicated by the middle dotted line) shows that the resistance value of the sheet resistor changes slightly. If only one monitoring point is used to monitor the phase change temperature based on the fluctuation of the sheet resistance, the sensitivity and accuracy will be low.

[0036] refer to Figure 2 , which shows a flow chart of a method for monitoring phase change temperature provided by an exemplary embodiment of the present application, such as Figure 2 As shown, the method includes:

[0037] Step 201, obtaining a first resistance value, the first resistance value being the square resistance of a first thin film layer when heat treated at a first preset temperature, the first thin film layer being formed on a first substrate, the first thin film layer including a titanium nitride layer and a titanium layer, and the first substrate including silicon.

[0038] Step 202, obtaining a second resistance value, where the second resistance value is the square resistance of the second thin film layer when heat treated at a second preset temperature, the second thin film layer is formed on a second substrate, the second thin film layer includes a titanium nitride layer and a titanium layer, the second substrate includes silicon, and the first preset temperature and the second preset temperature are not equal.

[0039] For example, in an embodiment of the present application, two wafers (substrates) can be prepared as test wafers, one being a first substrate and the other being a second substrate. Both the first substrate and the second substrate contain silicon. A titanium nitride layer and a titanium layer can be sequentially deposited on the first substrate by a chemical vapor deposition (CVD) process to form a first thin film layer. A titanium nitride layer and a titanium layer can be sequentially deposited on the second substrate by a CVD process to form a second thin film layer.

[0040] A first substrate formed with a first thin film layer is placed in a heat treatment device, the temperature of the heat treatment device is set to a first preset temperature, and heat treatment is performed at the first preset temperature. The square resistance of the first thin film layer is obtained at every preset time interval to obtain a first resistance value (the first resistance value is the square resistance curve sampled by time).

[0041] The second substrate formed with the second thin film layer is placed in a heat treatment device, the temperature of the heat treatment device is set to a second preset temperature, and heat treatment is performed at the second preset temperature. The square resistance of the second thin film layer is obtained at every preset time interval to obtain a second resistance value (the second resistance value is the square resistance curve sampled by time).

[0042] Among them, the value range of the first preset temperature can be [290 degrees Celsius, 300 degrees Celsius], for example, it can be 295 degrees Celsius; the value range of the second preset temperature can be [295 degrees Celsius, 310 degrees Celsius], for example, it can be 305 degrees Celsius.

[0043] Step 203: Monitor the temperature of the heat treatment according to the difference between the first resistance value and the second resistance value.

[0044] like Figure 3 As shown, when the difference between the first resistance and the second resistance (△R S ) is smaller, the temperature drift (△T) shifts to a negative value, that is, if the difference between the first resistance and the second resistance changes from high to low, it is determined that the temperature of the heat treatment is lower than the preset temperature; similarly, when the difference between the first resistance and the second resistance (△R S ) increases, the temperature drift (ΔT) shifts toward a positive value. That is, if the difference between the first resistor and the second resistor changes from low to high, it is determined that the heat treatment temperature is higher than the preset temperature. The actual monitored data can be compensated based on the above feedback results.

[0045] To summarize, in the embodiments of the present application, the substrate formed with a titanium nitride layer / titanium layer is heat-treated at different preset temperatures to obtain the block resistance of the thin film layer at different preset temperatures, and the temperature of the heat treatment is monitored according to the difference in block resistance of the thin film layer at different preset temperatures. Since the difference in block resistance at different preset temperatures is related to the temperature drift and is easy to detect, the problem of low monitoring sensitivity and accuracy caused by monitoring the phase change temperature based on block resistance at a single monitoring temperature in the related art is solved because the block resistance is not sensitive to small temperature fluctuations, thereby improving the accuracy of phase change temperature monitoring, thereby improving the stability of the process and the yield of the product.

[0046] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A method for monitoring phase change temperature, characterized in that: The method is applied to the preparation process of the nickel silicon layer, and the method comprises: Obtaining a first resistance value, where the first resistance value is a sheet resistance of a first thin film layer when heat treated at a first preset temperature, the first thin film layer being formed on a first substrate, the first thin film layer including a titanium nitride layer and a titanium layer, and the first substrate including silicon; Obtaining a second resistance value, where the second resistance value is a square resistance of the second thin film layer when the heat treatment is performed at a second preset temperature, the second thin film layer being formed on a second substrate, the second thin film layer including a titanium nitride layer and a titanium layer, the second substrate including silicon, and the first preset temperature and the second preset temperature being unequal; The temperature of the heat treatment is monitored according to the difference between the first resistance value and the second resistance value.

2. The method according to claim 1, characterized in that The step of monitoring the temperature of the heat treatment according to the difference between the first resistance value and the second resistance value includes: If the difference changes from high to low, it is determined that the temperature of the heat treatment is lower than the preset temperature.

3. The method according to claim 2, characterized in that The step of monitoring the temperature of the heat treatment according to the difference between the first resistance value and the second resistance value includes: If the difference changes from low to high, it is determined that the temperature of the heat treatment is higher than the preset temperature.

4. The method according to any one of claims 1 to 3, characterized in that: The obtaining of the first resistance value includes: placing the first substrate having the first thin film layer formed thereon in a heat treatment device, wherein the temperature of the heat treatment device is set to the first preset temperature; Performing heat treatment at the first preset temperature; The sheet resistance of the first thin film layer is obtained at every preset time interval to obtain the first resistance value.

5. The method according to claim 4, characterized in that The obtaining of the second resistance value includes: placing the second substrate having the second thin film layer formed thereon in the heat treatment equipment, wherein the temperature of the heat treatment equipment is set to the second preset temperature; performing heat treatment at the second preset temperature; The sheet resistance of the second thin film layer is acquired at each preset time interval to obtain the second resistance value.

6. The method according to claim 5, characterized in that The first preset temperature is greater than 290 degrees Celsius and less than 300 degrees Celsius.

7. The method according to claim 6, characterized in that The second preset temperature is greater than 295 degrees Celsius and less than 310 degrees Celsius.

Images