JP3519251B2 - Simulation equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing process simulation, and more particularly, to a technique for easily simulating a substance that causes an aggregation phenomenon in impurity diffusion or point defect diffusion simulation.

[0002]

2. Description of the Related Art As the degree of integration of integrated circuits increases, the number of manufacturing steps increases and the steps themselves become complicated. For this reason,
The number of prototypes has increased and the development cost has increased. In order to cope with such a situation, efforts are being made to reduce the number of trial productions and the trial production period by narrowing down the trial production conditions in advance using a simulator. A general simulation device is shown in FIG. This simulation device
An input unit 1 for inputting a process flow 10 in which a procedure, conditions, etc. of process processing relating to a semiconductor device to be manufactured are recorded
00 and a process simulation based on the input process flow, and outputs the device information 20 such as shape and impurity distribution information.
0, a device simulation section 300 that performs a device simulation based on the output element information 20, and an output section 400 that outputs the result of this device simulation.

Here, the process simulation section 20
In No. 0, simulation of ion implantation, oxidation / diffusion process, etc. was performed using a process simulator to predict the element shape and impurity distribution, and the process conditions for trial manufacture were narrowed down so that the results would be desired values.

Recently, it has been reported that phosphorus aggregates on the oxide film side of the silicon substrate / oxide film interface [Reference: M. Akazaw
a, T.Aoki, T.Tazawa, and Y.Sato, SISPAD'96 (1996) 2
9.]. Since the concentration of phosphorus near the surface of the substrate decreases due to this aggregation phenomenon, the threshold value of the PMOSFET, for example, greatly deviates from the actually measured value unless the aggregation phenomenon is incorporated in the simulation.

FIG. 5 is a diagram schematically showing the state of this aggregation phenomenon. The horizontal axis of the chart shows the depth from the surface,
The vertical axis represents the phosphorus concentration. As shown in the figure, the phosphorus concentration in the portion of the aggregation layer is higher than that in the portion of the oxide film. It is considered that the aggregation layer has a thickness of about 0.5 nm.

[0006]

In order to simulate this phenomenon including the oxidation step, the oxide film / aggregation layer /
It is necessary to solve the moving interface problem of a three-layer structure composed of a silicon substrate. The moving interface calculation that is normally performed is for a two-layer structure, and the program becomes very complicated to handle a three-layer structure. In particular, it is very difficult to modify an existing complex general-purpose process simulator. In particular, there has been a problem that it becomes more difficult as the simulation dimension becomes two-dimensional and three-dimensional.

The present invention has been made in view of the above circumstances, and an object of the present invention is to easily perform a simulation of a substance that causes an aggregation phenomenon and also to perform a two-dimensional and three-dimensional simulation. An object of the present invention is to provide a simulation method, a simulation device, and a computer-readable recording medium that records a simulation program that can be easily changed.

[0008]

In order to achieve the above object, the invention of claim 1 is a device for simulating the behavior of a substance that aggregates at an interface between a substrate of a semiconductor device and an oxide film, wherein the substance is After returning the aggregated layer to the interface between the substrate and the oxide film, which is moved by the substance reaction or diffusion simulation, as a means that the aggregated layer that is formed by aggregation does not exist. And a means for simulating the segregation of the above condition.

In the above configuration of the present invention, in the material reaction or diffusion simulation, it is calculated that there is no aggregation layer. By assuming that there is no cohesive layer in this way and performing the calculation, it is sufficient to perform simulation on a model having a two-layer structure, so that the simulation can be easily performed. After that, the segregation is calculated after the interface has moved by a substance reaction or a diffusion simulation in consideration of the agglomerated layer. Here, the material reaction includes an oxidation process and a silicidation process. Further, the substance that aggregates at the interface between the substrate of the semiconductor device and the oxide film includes phosphorus and arsenic.

According to a second aspect of the present invention, there is provided an apparatus for performing a process simulation of the semiconductor device based on a process flow representing a flow of a manufacturing process of the semiconductor device,
The process simulation unit has a process flow decoding unit that inputs the process flow and decodes the process flow, and a simulation control unit that performs a process simulation of the manufacturing process based on the decoding result of the process flow decoding unit. In the simulation of the substance reaction or diffusion process in the manufacturing process, the aggregated layer, which is a layer formed by aggregating substances, is regarded as an adjacent substance region, the substance reaction or diffusion is calculated, and the adjacent regions are calculated. Return the aggregation layer regarded as the material region to the original,
It is characterized in that a segregation calculation of an interface between the agglomerated layer and another substance region is performed.

In the configuration of the above-mentioned invention, the material reaction and the like are calculated by regarding the material region in which the interface moves along with the material reaction as the adjacent material region. Therefore, the calculation is performed in a smaller material region. Further, since it is regarded as the adjacent material region, even if the conventional simulation method is used, the aggregated portion does not give a calculation result such that the material is diffused. After that, the agglomerated portion is returned to the original state and the segregation is calculated. Thereby, the simulation can be easily performed.

According to the third aspect of the present invention, when the agglomeration layer is regarded as an adjacent substance region, the concentration of impurities or point defects in the substance region in which the interface moves is standardized by a segregation coefficient with the adjacent substance region. It is characterized in that the material region is converted into the adjacent material region.

Here, the segregation coefficient means a phenomenon in which the concentration of a certain substance is biased due to the difference in chemical potential at the interface of interest, and means the ratio of the bias. To normalize with the segregation coefficient means to temporarily remove the deviation by dividing the concentration in the region where the concentration is biased due to the difference in chemical potential by the segregation coefficient. By normalizing with the segregation coefficient in this way, it can be easily regarded as the adjacent material regions.

According to a fourth aspect of the present invention, when the agglomeration layer is regarded as an adjacent substance region, the concentration of impurities or point defects in the substance region where the interface moves is determined as the substance in which the concentration of the adjacent substance region is adjacent to the substance region. It is characterized in that it is regarded as the adjacent substance region by making the concentration equal to that of the region.

Here, making the concentrations equal means, for example,
This is an operation in which the difference between the concentration of a substance region in which the interface moves due to a substance reaction and the concentration of the adjacent substance region is obtained, and the difference is subtracted from the concentration of the substance region in which the interface moves due to the substance reaction. By doing so, it can be easily regarded as the adjacent material regions.

According to a fifth aspect of the present invention, when the agglomeration layer is regarded as an adjacent substance region and a substance reaction or diffusion is calculated, the substance region whose interface moves due to the substance reaction is subjected to a one-dimensional simulation. In this case, the length is set to zero, the area is set to zero in the case of two-dimensional simulation, and the volume is set to zero in the case of three-dimensional simulation. It is characterized by performing.

According to the configuration of the above invention, geometrical handling can be simplified. Further, it is not necessary to generate a mesh or the like for the substance area. Therefore, the simulation can be easily performed.

According to a sixth aspect of the present invention, in a method of simulating the behavior of a substance that agglomerates at an interface between a substrate of a semiconductor device and an oxide film, segregation of a substance region in the semiconductor device and a substance in the substance region are performed. A part of the reaction, the segregation of the substance region in the semiconductor device and the diffusion in the substance region, or the segregation of the substance region in the semiconductor device, the substance reaction in the substance region, and the diffusion in the substance region. It is characterized in that the simulation of the manufacturing process of the semiconductor is performed by obtaining a simulation result by a coarse coupling calculation in which the remainder is divided and calculated.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a simulation method, a simulation apparatus, and a computer-readable recording medium recording a simulation program according to the present invention will be described below in detail with reference to the drawings.

In the simulation method for explaining the embodiment described below, the CPU for performing various processes
An ordinary computer system including an input device such as a keyboard, a mouse, and a light pen, an external storage device such as a memory device, a disk device, and a floppy disk device, and an output device such as a printer device is used. The CPU includes an arithmetic unit that performs processing of each step described below and a main storage unit that stores an instruction of the processing.

First Embodiment FIG. 1 shows a process simulation apparatus of this embodiment. This process simulation apparatus includes a process flow decoding unit 210 that decodes the process flow 10 that records the procedure and conditions of process processing relating to a semiconductor device that is manufactured, and an ion implantation process simulation unit 221 that simulates the ion implantation process. An etching process simulation means 222 for simulating the etching process, a position process simulation means 223 for simulating the deposition process, and an oxidation / diffusion process simulation means 224 for simulating the oxidation / diffusion process in consideration of the agglomeration layer. And the like, based on the decoding result of the process flow decoding unit 210, a simulation control unit 220 that performs a process simulation while controlling these simulation means, It is as it has.

In this embodiment, a one-dimensional impurity diffusion simulation in a silicon substrate in an oxidizing atmosphere is used for simplification of description. It is assumed that an oxide film is formed on the silicon substrate and that an impurity aggregation layer exists between the oxide film and the silicon substrate. The impurity aggregation layer is located on the oxide film side of the interface and has a constant thickness.
Further, for simplicity, it is assumed that the impurity diffusion coefficient in the aggregation layer is the same as that in the oxide film.

FIG. 2 is a flow chart showing the processing operation of the oxidation / diffusion process simulation means 224 in consideration of the agglomerated layer of this embodiment. In the following description, an impurity diffusion simulation in an oxidizing atmosphere will be described.

First, when the simulation is started,
The diffusion time T is set to 0 (step S101).
Then, the aggregation layer between the oxide film and the substrate is temporarily regarded as an oxide film region (step S102). Here, the reason for temporarily considering the oxide film region is that if oxidation / diffusion calculation is performed while the concentration of the aggregation layer is high, a step due to segregation occurs in the impurity concentration of the oxide film and the aggregation layer. This is because the calculation result is such that the agglomerated substance diffuses into other regions.

As a method of considering the oxide film region, the impurity concentration in the oxide film is standardized by the segregation coefficient. That is, the segregation coefficient (ratio of the phosphorus concentration of the oxide film and the aggregation layer) is calculated,
The phosphorus concentration in the aggregation layer is divided by the segregation coefficient. The following oxidation / diffusion calculation is performed using the result of the division. As another method, the phosphorus concentration of the oxide film is made equal to that of the agglomerated layer, the difference is stored, and the oxidation / diffusion calculation is performed.

Subsequently, with respect to the oxide film and the silicon substrate,
Diffusion coefficient, segregation coefficient of oxidizing atmosphere at diffusion temperature,
Oxidation / diffusion calculation is performed by calculating the oxidation coefficient and the like to set a diffusion equation (step S103), and calculating the set diffusion equation (step S104).
At this time, the oxide film / substrate interface moves along with the calculation of oxidation.

Then, the aggregation layer is returned to the oxide film side of the moved oxide film / substrate interface (step S105). here,
When the phosphorus concentration of the aggregation layer is normalized by the segregation coefficient in step S102, the impurity concentration in the oxide film normalized by the segregation coefficient is returned to the physical concentration. As a specific operation, multiplication is performed using a segregation coefficient. If the phosphorus concentrations of the oxide film and the agglomeration layer are the same, the stored difference is added.

Subsequently, a segregation equation is set for the agglomerated layer and control volumes on both sides thereof (step S106), and the set segregation equation is solved to obtain an impurity distribution (step S107). In this way, by dividing the calculation of diffusion / oxidation and the calculation of segregation and solving them by coarse coupling, the complicated calculation can be simplified.

Subsequently, the diffusion time T is increased by ΔT (step S108), and it is judged whether or not the value exceeds the total diffusion time Tf (step S109). If it does not exceed the total diffusion time Tf, the loop starting from step S102 is executed again. Run, otherwise end simulation.

Since the calculation method by the coarse coupling may have a problem in calculation accuracy, the accuracy of the calculation method of the present invention was confirmed by comparing with the exact solution in the case where there is no interface movement. FIG. 3 is a chart showing a phosphorus concentration distribution when an oxide film of 20 nm is deposited and annealed on a substrate containing 10 ¹⁸ cm ³ of phosphorus uniformly. The horizontal axis of this chart shows the depth, and the vertical axis shows the concentration of phosphorus. Here, the triangle is the solution obtained by strictly solving the three-layer structure, the solid line is the solution according to the present embodiment, and the broken line is the exact solution for the oxide / substrate two-layer structure.

As is apparent from FIG. 3, when there is no interface movement, the present invention can perform simulation with extremely high accuracy. It is expected that the calculation will be performed with high accuracy even when the interface moves.

As described above, a simulation of a three-layer structure including a cohesive layer and the like can be easily realized by slightly modifying an existing general-purpose simulator that handles a moving interface of a two-layer structure.

In the above description, the aggregation layer is temporarily regarded as an oxide film, but it may be temporarily regarded as a silicon substrate. Also, in the above description, a two-layer structure of an oxide film and a silicon substrate was assumed for simplicity.
There may be other material regions such as an OI oxide film. Further, there may be a substance region that allows the oxidant to pass therethrough on the oxide film.

In this embodiment, it is assumed that the aggregation layer has a finite length (thickness), but the thickness of the aggregation layer may be zero in order to simplify the geometrical handling. In this case, it is not necessary to consider diffusion in the agglomerated layer.

Although the oxidation of the silicon substrate is taken as an example in the present embodiment, it can be applied to the silicide reaction of the silicon substrate. For example, with respect to a TiSi ₂ · TiSi / silicon substrate, TiSi ₂ is temporarily transferred to T at each time step.
The TiSi-silicon substrate reaction and impurity diffusion are calculated assuming that they are in the iSi region, and then TiSi ₂ is returned to TiSi.
The segregation and diffusion between ₂ and TiSi should be solved.

Second Embodiment Next, a simulation method and a simulation apparatus of the second embodiment will be described. In this embodiment,
A two-dimensional simulation will be described as an example. In this example, for the sake of simplicity, when oxidizing the silicon substrate, it is assumed that an impurity agglomeration layer having a thickness a is formed along the surface of the silicon substrate. The two-dimensional equation is solved using, for example, the finite element method using a triangular mesh. Therefore, the oxide film area,
A triangular mesh is set in the aggregation layer region and the silicon substrate region.

The simulation procedure of this embodiment will be described with reference to FIG. 2 used in the description of the first embodiment. In the present embodiment, a two-dimensional simulation will be described, but the procedure is almost the same as the one-dimensional simulation procedure. When the simulation is started, first, the diffusion time T is set to 0 (step S101).

Then, the aggregation layer between the oxide film and the substrate is temporarily regarded as an oxide film region (step S102). FIG. 4 is a diagram schematically showing a two-dimensional mesh. In this figure, the area S surrounded by the point ABD and the area T surrounded by the point ADC are assumed to be silicon substrate areas, and the area U surrounded by the point C′D′F and the area C′FE are surrounded by the point C′D′F. The enclosed area V is assumed to be the aggregation layer area, and the point E '
The region W surrounded by F′H and the region X surrounded by the point E′HG are oxide film regions. Here, the triangular meshes U and V in the aggregation layer are regarded as oxide film regions. At this time, the impurity concentration in the oxide film is normalized by the segregation coefficient of the oxide film / aggregation layer. That is, the vertices C ′, D ′,
The impurity concentrations of E and F are standardized.

Next, for the oxide film and the silicon substrate, the diffusion coefficient, the segregation coefficient, the oxidation coefficient, etc. of the oxidizing atmosphere at the diffusion temperature are calculated to set the diffusion equation (step S103). Then, in step S104, the diffusion equation is solved. At this time, the oxide film / substrate interface moves along with the oxidation.

In step S105, the moved oxide film
The aggregation layer is returned to the oxide film side of the substrate interface. Then, the standardized impurity concentration of the oxide film region is restored.

In step S106, a segregation equation is set for the aggregation layer, the oxide film in contact with the aggregation layer, and the triangular elements of the silicon substrate.

At this time, the diffusion between the triangular elements in the aggregation layer may be set. Next, in step S107, the segregation equation is solved to obtain the impurity distribution. In step S108, the diffusion time T is increased by ΔT, and it is determined whether or not the value exceeds the total diffusion time Tf (step S109). If it does not exceed, the loop starting from step S102 is executed again. End the simulation.

As described above, in the present embodiment, from one dimension to 2
Can be easily extended to dimensions. Similarly, it can be easily extended to three dimensions. In addition, the fact that two-dimensional simulation can be performed can be performed in a more realistic manner. Further, it becomes possible to perform a simulation of the dependency of the gate length of the semiconductor device.

In the present embodiment, it is assumed that the aggregation layer has a finite area, but the area of the aggregation layer may be zero in order to simplify the geometrical handling. In this case, it is not necessary to consider diffusion in the agglomerated layer. By thus reducing the area of the aggregation layer, there is an effect that it is not necessary to newly generate a mesh in the aggregation layer.

The program for implementing the above-mentioned simulation method can be stored in a recording medium. The recording medium can be read by a computer system, the program can be executed, and the simulation method described above can be realized while controlling the computer. Here, the recording medium is a memory device,
A device capable of recording a program, such as a magnetic disk device or an optical disk device, is included.

[0046]

As described above, the simulation method, the simulation apparatus, and the simulation method according to the present invention,
According to the computer-readable recording medium in which the simulation program is recorded, it is possible to easily perform the simulation of the substance causing the aggregation phenomenon,
Two-dimensional and three-dimensional simulations can be easily changed.

[Brief description of drawings]

FIG. 1 is a diagram showing a simulation apparatus of this embodiment.

FIG. 2 is a flowchart showing a simulation process of this embodiment.

FIG. 3 is a chart showing the calculation accuracy of the present invention. Here, a triangle is a solution obtained by strictly solving a three-layer structure, a solid line is a solution according to the present invention, and a broken line is an exact solution for an oxide film / substrate two-layer structure.

FIG. 4 schematically shows a two-dimensional mesh.

FIG. 5 is a diagram schematically showing how phosphorus is aggregated in an aggregate layer between an oxide film and a silicon substrate.

FIG. 6 is a block diagram showing a conventional simulation apparatus.

[Explanation of symbols]

10 process flow 20 element information 21 Shape information 22 Impurity distribution information 100 input section 200 Process Simulation Department 210 Process Flow Decoding Unit 220 Simulation control unit 221 Ion Implantation Process Simulation Means 222 Etching process simulation means 223 Deposition Process Simulation Means 224 Oxidation / diffusion process simulation means 300 Device Simulation Department 400 output section

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/22 H01L 21/316

Claims (5)

(57) [Claims] 1. A device for simulating the behavior of a substance that agglomerates at the interface between a substrate and an oxide film of a semiconductor device, wherein a substance reaction is performed assuming that there is no agglomeration layer which is a layer formed by agglomeration of the substance. Or, a means for performing diffusion simulation and movement by the substance reaction or diffusion simulation
And a means for simulating the segregation of the state after the aggregation layer is returned to the interface between the substrate and the oxide film . 2. A device for performing a process simulation of a semiconductor device based on a process flow representing a flow of a semiconductor device manufacturing process, a process flow decoding unit for inputting the process flow and decoding the process flow, based on the result of decoding process flow decryption unit, anda simulation control unit for process simulation of the production process, the process simulation unit, among the manufacturing processes, the simulation of material reaction or diffusion process, material The aggregation layer, which is a layer formed by aggregation, is regarded as an adjacent substance region, and a substance reaction or diffusion is calculated, and the aggregation layer regarded as the adjacent substance region is returned to the original state, and the aggregation layer is returned. Simulation characterized by performing the segregation calculation of the interface between the material and other material regions apparatus. 3. When the aggregation layer is regarded as an adjacent material region, the concentration of impurities or point defects in the material region where the interface moves is standardized by a segregation coefficient with the adjacent material region, and the adjacent material regions are adjacent to each other. The material region is regarded as a material region.
The described simulation device. 4. The concentration of impurities or point defects in the material region in which the interface moves is equal to the concentration of the adjacent material region when the concentration layer is regarded as the adjacent material region. The simulation apparatus according to claim 2, wherein the adjacent material regions are regarded as adjacent to each other. 5. When the agglomeration layer is regarded as an adjacent substance region and the calculation of the substance reaction or diffusion is performed, the length of the substance region in which the interface moves due to the substance reaction is increased in the case of one-dimensional simulation. The characteristic is that the material reaction or diffusion is calculated assuming that the area is zero, the area is zero in the case of two-dimensional simulation, and the volume is zero in the case of three-dimensional simulation. The simulation device according to claim 2.