KR940010908B1 - Operating method of semiconductor device - Google Patents

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Description

How semiconductor devices work

1A to 1F are schematic views showing a semiconductor device manufacturing process of the present invention.

2 is a diagram showing the state of nitrogen change in various nitride oxide films measured by Auger spectroscopy.

3A is a graph of drain current I _D versus gate driving voltage V _G -V _T at room temperature for an 7.7 nm thick oxide film and a nitride oxide film NO formed by nitriding at 950 ° C. for 60 seconds.

3b is a graph of the mutual conductance (g _m ) of the gate driving voltage (V _G -V _T ) at room temperature for an oxide film of 7.7 nm thickness and an oxide nitride film NO formed by nitriding at 950 ° C. for 60 seconds. .

4A is a graph of the drain current I _D versus the gate driving voltage (V _G -V _T ) at room temperature for an oxide film 7.7 nm thick and an oxide nitride film NO formed by nitriding at 950 ° C. for 60 seconds.

4b is a graph of the mutual conductance (g _m ) versus the gate driving voltage (V _G -V _T ) at 82K for an 7.7 nm thick oxide film and a nitride oxide film NO formed by nitriding at 950 ° C. for 60 seconds. .

5A and 5B are characteristic curves showing gate saturation currents at 82 K for the oxide film and the nitride oxide film formed by nitriding at 950 ° C. for 60 seconds.

Figure 6a is a graph of the maximum field effect mobility (μ _FEmax ) at room temperature with respect to the nitride time associated with various nitride oxide films.

6b is a graph of field effect mobility (μ _FE ) when a high vertical electric field of 3.3 MV / cm is formed in an insulating film with respect to the nitride time associated with various nitride oxide films used as the insulating film.

7A and 7B are graphs of effective mobility (μ _eff ) in a high vertical field of 3.3 MV / cm at room temperature and 82 K, respectively, versus nitriding time.

8 is a graph of the maximum nitriding time (t _N ) which achieves an improvement in the effective mobility compared to the oxide film against the nitriding temperature (T _N ).

9 is a graph of the effective mobility (μ _gff ) in a high vertical field of 4 MV / cm in an insulating film measured by Auger spectroscopy with respect to nitrogen concentration ([N] _int ) near the interface between the insulating film and the substrate.

* Explanation of symbols for main parts of the drawings

1: semiconductor substrate 2: thermal oxide film

3: oxide nitride film 4: isolation insulating film

5: gate electrode 6: source, drain region

7: inner layer insulating film 8: aluminum electrode

The present invention relates to a micro metal oxide semiconductor field effector (hereinafter referred to as a MOS device) and a method of operating the semiconductor device.

Previously, thermal oxide films formed on semiconductor substrates have been used as gate oxide films for MOS devices. In a micro MOS device using a conventional thermal oxide film as a gate insulating film, deterioration in mobility caused by an increase in an electric field acting in a direction perpendicular to a channel has become an important problem. The deterioration in mobility has been one of the main factors that hinder the miniaturization of MOS devices by reducing the current driving force and the switching speed of the MOS devices.

On the other hand, in order to improve the reliability of dielectric strength and the like, studies have been conducted using nitride oxide films instead of thermal oxide films in micro MOS devices. However, at the present time, since the mobility of the nitride oxide film is very low as compared with the thermal oxide film, this was a serious problem that prevents the practical application of the nitride oxide film.

The semiconductor device of the present invention for overcoming the above-described disadvantages and combinations comprises a semiconductor substrate and an insulating film arranged on the substrate, the insulating film being 10 ^{6.6-T / 225} seconds on the thermal oxide film formed on the substrate. It is characterized in that the nitride oxide film having a greater mobility than the thermal oxide film obtained by nitriding in an atmosphere made of nitriding gas for the following nitriding time, wherein T _N is preferably at most 1100 ℃ as the nitriding temperature at the Celsius temperature. The higher the ionicity, the shorter the nitriding time.

In a preferred embodiment, the nitride oxide film is used as the gate insulating film.

Another semiconductor device according to the present invention comprises a semiconductor substrate and an insulating film arranged on the substrate, wherein the insulating film is about 8 atomic percent or less near the interface of the substrate made by nitriding the thermal oxide film formed on the substrate. It is characterized in that it is a nitride oxide film having a peak nitrogen concentration of.

In a preferred embodiment, the nitride oxide film is used as the gate insulating film.

In the semiconductor device according to the present invention, when the driving voltage for generating an electric field in the lateral direction of the nitride oxide film is relatively low, the drain current and mutual conductance are not significantly different from those of the normal oxide film, but as the driving voltage increases, the mutual conductance is increased. The improvement is remarkable and a large drain current can be obtained. The intensity of the electric field E is proportional to the magnitude of the driving voltage V _G -V _T and inversely proportional to the thickness t of the oxide nitride film. That is, the electric field is determined by the formula E = (V _G -V _T ) / t. In operating the semiconductor device according to the present invention, the range of the electric field E for obtaining a large drain current by the effect of improving the mutual inductance is preferably 2 MV / cm ≦ E, more preferably the 2 MV / cm ≦. E≤7MV / cm, most preferably 4 / MV / cm≤E7MV≤ / cm.

A method of manufacturing a semiconductor device with a semiconductor substrate according to the present invention for overcoming the disadvantages and deficiencies of the prior art described above comprises the steps of: forming a thermal oxide film on a substrate, the thermal oxide film being 10 ^{6.6-T / 225 seconds} or less; Nitriding in an atmosphere composed of nitriding gas for a nitriding time of to obtain a nitriding oxide film having a higher mobility than the thermal oxide film, wherein T _N is most preferably 1100 ° C. as a nitriding temperature at Celsius. It is as follows.

In a preferred embodiment, metal heating by spinning means is used in the nitriding step.

Another manufacturing method of a semiconductor device composed of a semiconductor substrate includes forming a thermal oxide film on a substrate, nitriding the thermal oxide film in an atmosphere made of nitride gas, and about 8 tomic near the interface with the substrate. A step of obtaining a nitride oxide film having a peak nitrogen concentration of less than or equal to%.

In a preferred embodiment, metal heating by spinning means is used in the nitriding step.

Accordingly, the present invention described herein provides (1) a semiconductor device having a sub-micron MOS gate insulating film having superior performance as compared to a thermal oxide film; (2) It makes it possible to provide a method of manufacturing such a semiconductor device.

According to the present invention, it is possible to form a nitride oxide film having a high mobility as well as a markedly improved resistance to mobility deterioration due to a high vertical electric field in a very short time. In addition, redistribution of impurities formed on the semiconductor substrate can be prevented. Furthermore, the effective mobility in the high field can be improved by comparing with the thermal oxide film.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1F show a process for manufacturing a semiconductor device of the present invention. The semiconductor device is a MOS type and is manufactured as follows.

First, the isolation insulating film 4 is formed on the semiconductor substrate 1 made of silicon, as shown in FIG. 1A, for example, by local oxidation of silicon (LOCOS). Then, as shown in FIG. 1B, a thermal oxide film 2 is formed on the semiconductor substrate. The thermal oxide film 2 is converted into the nitride oxide film 3 by heating for a short time using a short time heating furnace in an ammonia gas environment, as shown in FIG. 1C.

Then, a gate electrode material such as polysilicon or the like is applied and etched on the entire surface to form the gate electrode 5. As a result, the source and drain regions 6 are formed in a self-aligning manner by the ion implantation method as shown in FIG. 1D.

Next, an inner layer insulating film 7 is applied to the entire surface to form contact holes for the source and drain regions 6 as shown in FIG. 1E, and then aluminum as shown in FIG. 1F. An electrode 8 is formed to be the MOS device of the present invention.

2 shows the nitrogen change state measured by an auger spectrometer in the nitride oxide film formed by nitriding for 120 seconds at temperatures of 950 ° C, 1050 ° C, and 1150 ° C, respectively. The sample used in the measurement corresponds to the nitride oxide film 3 shown in FIG. 1C. This nitride oxide film has a nitride oxide layer not only in the vicinity of the surface of the film but also near the interface between the insulating film and the semiconductor substrate, and the nitrogen concentration increases with higher nitriding temperature. In FIG. 2, it can be seen that a relatively high concentration of nitrogen can be introduced into the insulating film even if the nitriding time is short.

Next, samples of MOS devices having both a gate length and a gate width of 100 mu m were prepared as shown in FIG. 1f to test their electrical characteristics. The thickness of the gate oxide film formed at this time was 7.7 m.

3A and 3B, the drain current I _D and the mutual conductance g _m at the room temperature of the 7.7m thick oxide film and the nitride oxide film NO formed by nitriding at 950 ° C. for 60 seconds are shown in FIG. (V _G -V _T ) are respectively shown. In the case of the oxide film, due to the deterioration of the high mobility due to the high vertical electric field, when the gate driving voltage (1.5 V or more) is high, the deterioration of the mutual conductance is remarkable and the drain current is also low. On the other hand, in the case of the nitride oxide film NO, the maximum cross-conductance generated at a relatively low driving voltage (approximately 0.5 to 1 V) is almost the same as that of the oxide film, while the high gate driving voltage (1.5) forming a relatively high vertical electric field E is obtained. V and higher), a significant improvement in terms of the deterioration of the interconductance observed in the oxide film shows that a very large drain current can be obtained. That is, it can be seen that the electric field E at this time is equal to the driving voltage (V _G −V _T ) / oxide thickness (t) = 1.5 V or more / 7.7 mm = 2 MV / cm or more.

4A and 4B show drain current I _D and interconductance g _m when operated at 82K, the temperature close to the boiling point of nitrogen, for the same sample shown in FIGS. 3A and 3B. Are respectively shown in relation to the gate driving voltages V _G -V _T. In the case of the oxide film, the mutual conductance decreases significantly when the gate driving voltage (1.5 V or more) is high, and the drain current is low at room temperature. The oxide film also exhibits a negative cross-conductance when the drain current decreases as the gate driving voltage increases. This is because as the temperature decreases, the deterioration of mobility caused by the high vertical electric field becomes larger. On the other hand, in the case of the nitride oxide film NO, the maximum mutual conductance generated at a relatively low driving voltage (approximately 0.5 to 1V) is slightly smaller than the mutual inductance of the oxide film, but since the negative cross-conductance observed in the oxide film does not exist, the high gate At the driving voltage (more than 1.5V), the drain current becomes larger in the case of the oxide film. In this case too, electric field (E) It can be seen that the desired result is obtained when the 2MV / cm.

By using a nitride oxide film (NO) as shown in Figs. 3a, 3b, 4a and 4b in the micro MOS device, the deterioration of mobility in a high vertical electric field can be significantly reduced, so that a thermal oxide film is used in actual use. A useful advantage is that the current driving force is higher and the circuit operation speed is faster than the case.

Notable improvements in such performance can also be observed with saturation current characteristics. 5A and 5B show the saturation current characteristics at each 82K of the oxide film and the nitride oxide film formed by nitriding at 950 ° C. for 60 seconds.

In the case of an oxide film, the mutual conductance is very small, and the drain current is lowered at a significantly higher gate drive voltage (3V or more). This is because of the intrinsic characteristics of the negative interconductance in the oxide film described above. On the other hand, in the case of the nitride oxide film NO, a sufficiently large drain current can be obtained since the sufficiently improved resistance to deterioration of the mutual conductance at a significantly high gate driving voltage (3 V or more).

In order to test the dependence of the field effect mobility on the nitriding conditions, FIGS. 6a and 6b show the maximum field effect mobility at room temperature, and FIG. 6b shows the high vertical electric field of 3.3 MV / cm in the insulating film. Field effect mobility is plotted against nitriding time. The field effect mobility (μ _FE ) is defined as follows.

Where L = channel length, W = channel width, V _D = drain voltage, C ₁ = capacitance per unit area of insulating film, I _D = drain current, and V _G -V _T = gate driving voltage. Since the field effect mobility (μ _FE ) is regarded as the mobility for the small signal, the mobility is clearly reflected at each voltage V _G -V _T.

As is apparent from FIG. 6A, the maximum effect mobility at a low driving voltage (approximately 0.5 to 1 V) becomes very large in the case of an oxide film, and as the nitriding proceeds, that is, the nitriding time increases or the nitriding temperature increases. Accordingly. On the other hand, as is apparent from FIG. 6B, the field effect mobility in a high vertical field of 3.3 MV / cm is significantly increased even if the nitriding time is very short. For example, when nitrided for only 15 seconds at 950 ° C, the mobility obtained in the high field is approximately twice that obtained in the case of the oxide film.

If nitriding continues for a long time, the improved field effect mobility in the high field changes very small. In this way, nitriding provides improved resistance to deterioration of the field effect mobility inherent in the high electric field in the oxide film, and as shown in FIG. 2, the nitride oxide layer formed near the interface by nitriding has the above-described field effect mobility. Will contribute greatly to the practical improvement of the

7a and 7b show the nitriding time for the experiment that the effective mobility in the high vertical electric field of 3.3 MV / cm at 82K depends on the nitriding conditions. The effective mobility (μ _FE ) is determined as follows.

In contrast to the above mentioned field effect mobility (μ _FE ), the effective mobility (μ _EFF ) is considered as the mobility for the large signal and is considered to more accurately represent the actually measured circuit operating speed. The effective mobility is influenced by the maximum field effect mobility (μ _FEmax ) and the field effect mobility (μ _FE ) in the high field. The relationship between the effective mobility (μ _eff ), the maximum field effect mobility (μ _FEmax ) and the field mobility in the high field (μ _FE ) is defined as follows.

Here, (V _G -V _T ) _max is a gate driving voltage when µ _FEmax is obtained. As is apparent from FIG. 7A, the effective mobility at each nitriding temperature is initially increased, reaches a maximum after a certain nitriding time, and then gradually decreases. High nitriding temperatures allow this trend to proceed in a short time. In a low nitriding state, for example, a shorter nitriding time, the field effect mobility in the high electric field is improved in a very short time as compared with the deterioration of the maximum field effect mobility as shown in FIG. The effective mobility is improved to obtain a larger driving current. On the other hand, in a high nitriding state, for example, a longer nitriding time, the influence on the deterioration of the maximum field mobility becomes greater, resulting in smaller effective mobility than the oxide film, resulting in deterioration of the drive current. Figure 7b applies to the case measured at 82K to show the trend as observed at room temperature. However, the range of nitriding time, which has a greater effective mobility than the oxide film, is obtained narrower and more precisely than in the case of room temperature.

In FIG. 8, the maximum nitriding time t _{N at} which the effective mobility is improved compared to the oxide film is shown with respect to the nitriding temperature T _N (° C.). As evident from Figure 8 the t _N = 10 ^{6.6-T / 225} relationship is at room temperature. This means that a nitride time of 10 ^{6.6-T / 225} or less should be selected to form the nitride oxide film so that the operation speed of the circuit which is superior to the oxide film can be achieved.

In this relational formula (t _N = 10 ^{6.6-T / 225} ) calculated from FIG. 8, the calculation of the nitriding time in the temperature range of 900 to 1200 ° C is shown in Table 1 below.

TABLE 1

9 shows a graph showing the effective mobility (μ _eff ) in a high vertical field of 4.0 MV / cm measured by an auger spectroscopy with respect to the nitrogen concentration ([N] _int ) near the interface between the insulating film and the substrate. . The nitride oxide film used as the MOS field effect device gate insulating film was formed by heating in ammonia gas environment for a short time using a short time heating furnace. As is apparent from FIG. 9, as the nitrogen concentration ([N]) increases in the effective mobility (μ _eff ), the maximum nitrogen concentration is about 2 to 3%, and then gradually decreases.

As can be seen from the diagram, the nitride oxide film having a nitrogen concentration ([N] _int ) of about 8 atomic% or less can be used to improve the effective mobility in high electric field which is useful for actual circuit operation as compared with the thermal oxide film. have.

As described above, according to the present invention, an insulating film having high mobility can be obtained by a very simple method. By using such an insulating film in a micro MOS device to sufficiently reduce the deterioration of the mobility in the high vertical electric field, in practical use, a useful advantage for higher current driving force and faster circuit operating speed is provided.

It is to be understood that the present invention can be readily made by those skilled in the art without departing from the scope and spirit of the invention.

Accordingly, the appended claims are not intended to be limited to the description set forth but rather to include all features of patentable novelty in the invention, including all features that would be treated equally by those skilled in the art. Should be interpreted as

Claims (16)

In the method of operating a semiconductor device, the semiconductor device includes a semiconductor substrate 1, an insulating film 3 formed on the substrate 1, a gate electrode 5 disposed on the insulating film 3, And a drain 6 and a source 6 formed in the substrate 1, wherein the insulating film 3 comprises 10 ^6.6- T _N ²²⁵ seconds or less of the thermal oxide film 2 formed on the substrate 1; A nitride oxide film obtained by nitriding in a nitriding gas atmosphere during a nitriding time of, wherein T _N is a nitriding temperature at a celsius degree having a range of 900 ° C. ≦ T _N ≦ 1150 ° C .; The semiconductor device is operated at a gate driving voltage (V _G -V _T ) which provides an electric field (E) in the range of 2 MV / cm≤E in the horizontal direction of the nitride oxide film 3. . The method of claim 1, wherein the gate driving voltage (V _G -V _T ) is characterized in that to provide an electric field (E) in the range of 2MV / cm ≤ E ≤ 7MV / cm in the transverse direction of the nitride oxide film (3). Method of operation of semiconductor device. The method of claim 2, wherein the gate driving voltage (V _G -V _T ) is characterized in that the electric field (E) in the range of 4MV / cm ≤ E ≤ 7MV / cm in the transverse direction of the nitride oxide film (3) Method of operation of semiconductor device. The method of operating a semiconductor device according to any one of claims 1 to 3, wherein the semiconductor device is operated at room temperature. The method of operating a semiconductor device according to any one of claims 1 to 3, wherein the semiconductor device is operated at a temperature near a boiling point of nitrogen. In the method of operating a semiconductor device, the semiconductor device includes a semiconductor substrate 1 and an insulating film 3 formed on the substrate 1, wherein the insulating film 3 is formed on the substrate 1. A nitride oxide film 3 formed by nitriding the formed thermal oxide film 2 in a nitriding gas atmosphere and having a nitrogen concentration of about 8 atomic% or less near the interface with the substrate; The semiconductor device is operated at a gate driving voltage (V _G -V _T ) which provides an electric field (E) in the range of 2 MV / cm≤E in the horizontal direction of the nitride oxide film 3. . The method of claim 6, wherein the gate driving voltage (V _G -V _T ) is characterized in that to provide an electric field (E) in the range of 2MV / cm ≤ E ≤ 7MV / cm in the transverse direction of the nitride oxide film (3). Method of operation of semiconductor device. The method of claim 7, wherein the gate driving voltage (V _G -V _T ) is characterized in that the electric field (E) in the range of 4MV / cm ≤ E ≤ 7MV / cm in the transverse direction of the nitride oxide film (3) Method of operation of semiconductor device. The method of operating a semiconductor device according to any one of claims 6 to 8, wherein the semiconductor device is operated at room temperature. The method of operating a semiconductor device according to any one of claims 6 to 8, wherein the semiconductor device is operated at a temperature near a boiling point of nitrogen. In the semiconductor device, a semiconductor substrate 1, an insulating film 3 formed on the substrate 1, a gate electrode 5 disposed on the insulating film 3, and a drain formed in the substrate 1 And a source 6; The insulating film 3 is a nitride oxide film obtained by nitriding a thermal oxide film 2 formed on the substrate 1 in a nitriding gas atmosphere for a nitriding time of 10 ^6.6- T _N ²²⁵ seconds or less, wherein T _N is 900. ℃ ≤T _N semiconductor device characterized in that the nitriding temperature in degrees C in the range of ≤1150 ℃. In the semiconductor device, the semiconductor device includes a semiconductor substrate 1, an insulating film 3 formed on the substrate 1, a gate electrode 5 disposed on the insulating film 3, and the substrate ( A drain and a source 6 formed in 1); The insulating film 3 is characterized in that the nitride oxide film 3 having a nitrogen concentration of about 8 atomic% or less near the interface with the substrate, which is made by nitriding the thermal oxide film 2 formed on the substrate 1. Semiconductor device. A method of manufacturing a semiconductor device, comprising: forming an insulating film 3 on a semiconductor substrate 1, forming a gate electrode 5 disposed on the insulating film 3, and forming the semiconductor substrate 1. Forming a source and drain region (6) therein; The insulating film is formed by nitriding a thermal oxide film 2 formed on the substrate 1 in a nitriding gas atmosphere for a nitriding time of 10 ^6.6- T _N ²²⁵ seconds or less, where T _D is 900 ° C. ≦ T _N A method of manufacturing a semiconductor device, characterized in that the nitriding temperature at a degree Celsius having a range of ≤1150 ℃. The method of manufacturing a semiconductor device according to claim 11, wherein in the nitriding step, metal heating by radiating means is used. A method of manufacturing a semiconductor device, comprising: forming an insulating film 3 on a semiconductor substrate 1, forming a gate electrode 5 on the insulating film 3, and forming a semiconductor substrate 1 on the semiconductor substrate 1. Forming source and drain regions 6 in the trenches; The insulating film is formed such that the thermal oxide film 2 formed on the substrate is nitrided in a nitride gas atmosphere to have a nitrogen concentration of about 8% or less near the interface with the substrate 1. Way. The method of manufacturing a semiconductor device according to claim 12, wherein in the nitriding step, rapid heating by radiating means is used.