JP4570494B2 - Etching simulation method and etching simulation apparatus - Google Patents

Description

The present invention relates to an etching simulation method and apparatus for evaluating an etching phenomenon in a wet etching method.

As semiconductor chips are highly integrated, there is an increasing demand for higher currents in addition to higher wiring density in circuit boards that connect semiconductor chips. As the circuit board becomes a use environment with a larger current, the copper substrate is made thicker, and for example, conventionally, a copper plate having a thickness of 15 μm to 150 μm is mainly used. A thick copper plate having a thickness of 200 μm or more may be used to cope with current.

With the above-mentioned increase in density, increase in current, or increase in copper thickness, some problems have become prominent. One of the problems is that side etching becomes more prominent. Side etching is a phenomenon in which etching is performed in the direction perpendicular to the copper thickness on the lower side of the resist film during etching in the copper thickness direction. In order to increase the density and thickness of the circuit board, This is one of the major obstacles.

Also, variations in the etching process are an obstacle to higher density. The fact that the etching effect differs greatly at the position on the substrate, such as the distribution and concentration of the solution during etching differing at the position on the substrate, is a factor that increases the defect rate of the circuit board. In particular, strict uniformity is required for high-frequency substrates.

Therefore, in order to optimize the etching process in response to new needs such as higher density and higher current, it is required to capture the etching phenomenon as accurately as possible and determine the optimal control parameters for the etching equipment. Yes. In order to serve such a purpose, development of a simulation technique for evaluating an etching phenomenon based on a theoretical calculation formula or the like is underway.

Patent Document 1 provides a simulation method for calculating the tip trajectories of a plurality of nozzles mounted in an etching chamber and calculating the liquid flow distribution on the substrate.

In Non-Patent Document 1, the locus of the etchant is calculated by calculating the nozzle trajectory, and the results of studies on optimization of the nozzle arrangement and optimization of the nozzle swing speed based on the results are reported. Has been.

JP-A-5-59576 “High-precision etching conditions in the continuous circuit formation method”, Koji Sato, Shuji Kitagawa, Matsushita Electric Engineering Technical Report, August 2001, p82-87

However, the above conventional techniques have the following problems.
That is, the etching effect is determined by the flow rate and concentration of the etching solution on the copper surface, but it is very difficult to predict the local flow near the pattern due to the influence of the resist and the like. In addition, although etching waste liquid becomes a hindrance to etching, there has never been a report that directly simulates the concentration of waste liquid.

Although Patent Document 1 predicts a two-dimensional liquid flow distribution of an etching solution on a substrate, it cannot predict a local flow near the pattern. Further, there is a problem that the concentration of the waste liquid cannot be calculated and the shape of the cavity formed by etching cannot be known.

Non-Patent Document 1 calculates the distribution of the etching liquid, but the state of the liquid flow is not calculated, and thus the time course cannot be known. Further, the local flow near the pattern, the concentration of the waste liquid, and the like are not calculated, and the shape of the cavity cannot be known.

Therefore, the present invention has been made to solve these problems. In addition to predicting the flow rate of the etching solution and the concentration of the waste solution on the substrate, the local flow near the pattern and the etching progress rate of the cavity are provided. Another object of the present invention is to provide an etching simulation method and an etching simulation apparatus for predicting a shape change and the like.

A first aspect of the etching simulation method of the present invention relates to an etching process in which a cavity is formed in the substrate by transporting the substrate into an etching chamber provided with a plurality of nozzles for spraying an etching solution. An etching simulation method for calculating a flow rate of an etchant during processing, an etch rate and an etch factor of the cavity, and a shape and drive design value related to the nozzle and the substrate, and etching near the cavity calculated separately A macro state calculation unit that calculates a flow rate distribution of the etching solution on the substrate from the local flow rate of the solution, the flow rate distribution calculated by the macro state calculation unit, the shape design value of the cavity, and the temperature of the etching solution And a physical property value, a shape is formed at a predetermined position on the substrate. The etch rate and etch factor of the cavity to be calculated, the local flow rate of the etchant in the vicinity of the cavity is calculated and output to the macro state calculation unit, and the flow rate of the etchant An etching simulation method characterized in that the distribution, the etch rate and etch factor of the cavity are integrated and calculated.

According to a second aspect, the macro state calculation unit calculates an average liquid thickness calculating means for calculating an average liquid thickness of the etching liquid on the substrate based on the drive design value of the nozzle, and the shape of the nozzle. And a nozzle trajectory calculating means for calculating the position and orientation of the nozzle based on the drive design value, and a spray amount distribution on the substrate from the position and orientation of the nozzle calculated by the nozzle trajectory calculating means. From the spray amount distribution calculating means, the average liquid thickness calculated by the average liquid thickness calculating means, the spray amount distribution calculated by the spray amount distribution calculating means, and the local flow velocity input from the micro state calculating unit, A flow velocity distribution calculating means for calculating a flow velocity distribution of the etching liquid on the substrate, wherein the micro state calculating section calculates the local flow velocity based on the average liquid thickness calculated by the average liquid thickness calculating means. Based on the local flow rate calculated by the local flow rate calculation unit, the flow rate calculation unit, and an etching state amount calculation unit for calculating the etch rate and etch factor of the cavity and the local concentration of the etching solution and the waste solution. An etching simulation method characterized by comprising:

According to a third aspect, the concentration distribution of the etching solution is calculated from the flow velocity distribution calculated by the flow velocity distribution calculation unit and the local concentration of the etching solution and the waste solution in the vicinity of the cavity calculated by the etching state calculation unit. The etching simulation method is characterized in that a concentration distribution calculation means for calculating the above is added to the macro state calculation unit.

In a fourth aspect, the micro state calculation unit preliminarily stores a predetermined table in which the etch rate and the etch factor are set using the local flow rate of the etchant, the shape design value of the cavity, and the etching processing time as parameters. An etching simulation method comprising: calculating an etch rate and an etch factor of the cavity based on the predetermined table.

A fifth aspect is characterized in that the predetermined position on the substrate targeted by the micro state calculation unit is any one point or two or more points on the substrate designated in advance. This is an etching simulation method.

A sixth aspect is an etching simulation method characterized in that the predetermined position on the substrate targeted by the micro state calculation unit is all points on the substrate.

The seventh aspect is the input unit for inputting the shape and drive design value of the substrate and the nozzle, the shape design value of the cavity, and the temperature and physical property value of the etching solution, and An etching simulation apparatus comprising: an arithmetic processing unit that performs a predetermined calculation according to the etching simulation method according to any one of items 6; and an output unit that outputs a calculation result of the arithmetic processing unit. It is.

An eighth aspect is an etching simulation apparatus, wherein the output unit includes image display means for imaging and displaying the flow velocity distribution and the etch factor calculated by the arithmetic processing unit. .

According to the present invention, the flow velocity distribution and the concentration distribution of the etching solution of the entire substrate are calculated by macro simulation, and the progress of the cavity shape formed on the substrate can be evaluated by micro simulation. It becomes possible.

In particular, the macro simulation and the micro simulation are performed by alternately using the calculation result of the other, and the overall phenomenon of the etching process and the local phenomenon are integrated and evaluated. It is possible to provide an etching simulation method and an etching simulation apparatus capable of performing the above.

Furthermore, by comprehensively handling the design conditions in the etching process (nozzle spray amount distribution, swinging period, substrate transfer speed, cavity shape, etc.), it is possible to provide design guidelines that are excellent in terms of manufacturing and cost.

An etching simulation method and an etching simulation apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

First, an outline of the etching process will be described. FIG. 2 is a view schematically showing an etching apparatus for performing an etching process on a copper substrate, and shows a plan view seen from above. As the etching apparatus 300, a plurality of nozzles 301 for spraying an etching solution and a pipe 302 for supplying the etching solution to each nozzle 301 are illustrated in FIG.

The copper substrate 303 to be etched is in close contact with a resist having a predetermined pattern drawn on the surface, and is conveyed under the nozzle 301 in the direction of an arrow 304 at a predetermined speed. The copper substrate 303 is a uniform one having a predetermined thickness.

The nozzle 301 is disposed at an upper portion of a predetermined height from the copper substrate 303 and has a structure in which an etching solution is sprayed from the nozzles 301 onto the surface of the copper substrate 303. FIG. 2 shows a range 305 in which the etching solution is sprayed from the nozzles 301 onto the surface of the copper substrate 303.

As a nozzle driving method, a swing type and a parallel movement type are generally known. FIG. 2 shows the swing type, and the nozzle 301 periodically swings around a pipe 302 within a predetermined angle range. That is, it is configured to repeatedly rotate repeatedly within a range of a predetermined angle on a plane perpendicular to the pipe 302 around a perpendicular line dropped from the nozzle 301 to the copper substrate 303. On the other hand, in the case of the parallel movement type, the nozzle 301 repeatedly moves in the direction perpendicular to the traveling direction of the copper substrate 303 together with the piping. As a nozzle driving method, a combination of both a swing type and a parallel movement type may be used.

The distance between the nozzles 301 (pitch) and the distance between the nozzle 301 and the copper substrate 303 are determined by spraying the etching solution as evenly as possible onto the copper substrate 303 in consideration of the spraying range 305, the transport speed of the copper substrate 303, and the like. Has been determined to be. Further, when the nozzle 301 is driven by the swing type, the swing angle and the rotational speed are the swing movement type when the translational movement type and the movement distance and the movement speed are combined. In this case, the deflection angle, rotational speed, moving distance and moving speed of the nozzle 301 are determined so that the etching solution is sprayed as evenly as possible.

Next, a process of forming a cavity in the copper substrate 303 by the etching process will be described with reference to FIG. FIG. 3 is a diagram schematically illustrating a process in which the copper substrate 303 is etched and a cavity 314 is formed in a local portion of the copper substrate 303. The resist 311 is in close contact with the surface of the copper substrate 303 at a position where a circuit pattern is to be formed, and the resist 311 is not in close contact with other positions.

It is shown that the etching solution 312 is sprayed from above the copper substrate 303, and the etching solution 312 forms a flow in the direction of the arrow 313 on the upper surface of the copper substrate 303. The etching solution 312 is distributed on the copper substrate 303 with a substantially uniform thickness. On the copper substrate 303 at a position where the resist 311 is not in close contact, the copper is dissolved by the etching solution 312 to form a cavity 314.

The cavity 314 is desirably formed only at a position where the resist 311 is not in close contact. However, since the etching solution 312 that has flowed into the cavity 314 also dissolves the side surfaces of the cavity 314, the cavity advances to a position where the resist 311 is in close contact. This is a side etch phenomenon. In FIG. 3, a side etch phenomenon is observed at a position 315.

A simulation method for quantitatively analyzing the phenomenon caused by the etching process described with reference to FIGS. 2 and 3 based on a predetermined theoretical formula will be described below. FIG. 1 is a process flowchart for explaining an embodiment of the etching simulation method of the present invention.

The simulation method according to the present embodiment includes a macro state calculation unit 100 and a micro state calculation unit 200. The macro state calculation unit 100 evaluates the event of the entire etching process shown in FIG. 2, calculates the direction of the nozzle 301 and calculates the distribution of the spray amount on the copper substrate 303, and from this, on the copper substrate 303 The flow rate distribution of the etching solution is obtained.

On the other hand, the micro state calculation unit 200 evaluates an event around the local portion where the cavity 314 shown in FIG. 3 is formed. The etching rate and etch factor of the cavity 314 and the flow rate of the etching solution 312 in the vicinity of the cavity 314 The concentration and further the concentration of the waste liquid are calculated.

The macro state calculation unit 100 includes a macro state calculation condition setting unit 110, an average liquid thickness calculation unit 120, a nozzle locus calculation unit 130, a spray amount distribution calculation unit 140, a flow velocity distribution calculation unit 150, a concentration distribution calculation unit 160, and a macro state. It consists of quantity output means 170.

The macro state calculation unit 100 according to the present embodiment includes the concentration distribution calculation unit 160, but may be an embodiment that does not use the concentration distribution calculation unit 160. In this case, the concentration of the etching solution 312 and the concentration of the waste solution are not calculated.

The macro state calculation condition setting unit 110 is a unit for setting data relating to the operating conditions of the etching apparatus 300. The operating conditions of the etching apparatus 300 include the size of the copper substrate 303, the conveyance speed of the copper substrate 303, the arrangement position of the nozzle 301, the spray amount distribution of the nozzle 301, and the movement condition of the nozzle 301. The movement conditions of the nozzle 301 include a deflection angle and a rotation speed in the case of the swing type, and a movement distance and a movement speed of the nozzle 301 in the case of the parallel movement type.

The average liquid thickness calculation unit 120 calculates the average liquid thickness of the etching liquid 312 on the copper substrate 303 based on the spray amount distribution of the nozzle 301 set by the macro state calculation condition setting unit 110. Here, assuming that the liquid surface pressure is 0 Pa, the average liquid thickness is calculated using Bernoulli's equation and Blasius' equation. The liquid thickness of the etching liquid 312 is assumed to be constant over the entire copper substrate 303, and the average liquid thickness calculated here is used in the subsequent calculations.

The nozzle trajectory calculation unit 130 inputs the arrangement position of the nozzle 301 and the movement condition from the macro state calculation condition setting unit 110, creates an equation representing the trajectory of the nozzle 301 based on the position, and based on the equation. Thus, the position and orientation of the spray nozzle of the nozzle 301 at each time point are calculated.

The spray amount distribution calculating unit 140 calculates a region 305 where the etching solution is sprayed from each nozzle 301 and reaches the copper substrate 303 from the position and orientation of the spray port calculated by the nozzle locus calculating unit 130. . Here, it is assumed that the range in which the etching solution is sprayed from the nozzle 301 is, for example, a triangular pyramid having the spray port of the nozzle 301 as an apex, and a surface where the triangular pyramid and the copper substrate 303 intersect is defined as a spray region 305. can do.

The spray amount distribution calculating means 140 further identifies the nozzle 301 to which the etching solution 312 is sprayed for each point (calculation grid) on the copper substrate 303 from the spray region 305 of each nozzle 301 calculated above. Based on the above, the spray amount distribution of the etching solution 312 is calculated.

The flow velocity distribution calculating unit 150 uses the Navier-Stokes equation based on the average liquid thickness calculated by the average liquid thickness calculating unit 120 and the spray amount distribution calculated by the spray amount distribution calculating unit 140. The flow velocity distribution of 312 is calculated. Further, when a local flow rate of the etching solution 312 in the vicinity of the cavity calculated by the micro state calculation unit 200 described later is given, the flow rate distribution reflecting the local flow rate as a pressure loss is calculated. .

The concentration distribution calculating means 160 uses the flow velocity distribution calculated by the flow velocity distribution calculating means 150 and the concentrations of the etching liquid 312 and the waste liquid in the vicinity of the cavity calculated by the micro-state calculating section 200 described later. The concentration distribution of the etching solution 312 over the entire substrate 303 is calculated.

The macro state quantity output means 170 is for outputting the flow velocity distribution and the concentration distribution of the etching solution 312 calculated above to an external display device or the like. The macro state quantity output unit 170 also outputs the flow velocity distribution and the concentration distribution to the micro state calculation unit 200.

Next, the micro state calculation unit 200 will be described below. The micro state calculation unit 200 includes a micro state calculation condition setting unit 210, a local flow velocity calculation unit 220, an etching state calculation amount unit 230, and a micro state amount output unit 240.

The micro state calculation condition setting unit 210 sets the shape design value of the cavity 314, the temperature and physical property values of the etching solution 312. The physical properties of the etching solution 312 include hydrochloric acid concentration and viscosity. Further, the micro state calculation condition setting unit 210 designates the position on the copper substrate 303 to be evaluated by the following calculation units.

The position to be evaluated by the micro state calculation unit 200 may be any one point on the copper substrate 303. For example, a plurality of points in the center and the periphery of the copper substrate 303 may be selected and specified. Good. Furthermore, all points on the copper substrate 303 may be used.

Based on the average liquid thickness calculated by the average liquid thickness calculation means 120, the local flow velocity calculation means 220 calculates the local flow velocity at the point using the Navier-Stokes equation.

The etching state quantity calculation means 230 calculates the dissolution amount of the copper substrate 303 based on the local flow velocity calculated by the local flow velocity calculation means 220, and from this, the etch rate of the cavity 314, the etch factor, and the etchant 312. The local concentration of the waste liquid is calculated.

The micro state quantity output unit 240 outputs the etch rate, the etch factor, and the local concentration calculated above to an external display device or the like. The micro state quantity output means 240 also outputs the local flow velocity and the local concentration to the macro state calculation unit 100.

The macro state calculation unit 100 and the micro state calculation unit 200 are executed while advancing time by a predetermined time width, and the calculation ends when a predetermined etching processing time is reached. In addition, the macro state calculation unit 100 and the micro state calculation unit 200 perform calculations alternately while using the other calculation result, and evaluate the overall phenomenon and local phenomenon of the etching process. I can do it.

According to the etching simulation method of the present embodiment configured as described above, the flow velocity and cavity diffusion in the local region near the cavity 314 are obtained using the flow velocity distribution on the copper substrate 303 evaluated by the macro state calculation unit 100. The process can be calculated, and the cavity shape change from moment to moment can be predicted.

As another embodiment of the present invention, a predetermined table created in advance can be used in place of the etching state amount calculation means 240 of the micro state calculation unit 200. In the predetermined table, the etch rate and the etch factor are set using the local flow rate of the etching solution 312, the shape design value of the cavity 314, and the etching processing time as parameters.

In the present embodiment, based on the predetermined table created as described above, the local flow velocity calculated by the local flow velocity calculation means 230 and the cavity 314 set by the micro state calculation condition setting means 210 are described. The etch rate and the etch factor of the cavity 314 are calculated from the shape design value and the etching processing time calculated by integration in the simulation. By using such a predetermined table, an effect that the calculation time can be significantly increased can be obtained.

An embodiment of the etching simulation apparatus of the present invention is shown in FIG. The etching / simulation apparatus 400 includes an input unit 410, an arithmetic processing unit 420, and an output unit 430.

The input unit 410 provides a means for inputting data set by the macro state calculation condition setting unit 110 and data set by the micro state calculation condition setting unit 210. Each of the data input at the input unit 410 is output to the arithmetic processing unit 420. Further, the input unit 410 provides a means for inputting a position on the copper substrate 303 to be evaluated by the micro state calculation unit 200.

The arithmetic processing unit 420 includes a CPU having a predetermined performance, a storage device, and the like, and executes a program created based on the etching simulation method of the present invention.

The output unit 430 is for outputting a calculation result obtained by executing the program in the arithmetic processing unit 420, and includes the flow velocity distribution, the concentration distribution, the etch rate, the etch factor, and the local concentration. Etc. are provided to the outside.

In the present embodiment, the output unit 430 includes an image display unit 431, and the calculation result can be displayed as an image. An example of image display is shown in FIG. FIG. 5A is an image of the flow velocity distribution, and FIG. 5B is an image of the cavity 314 formed in the copper substrate 303 based on the etch factor. It is.

By using such an image display, it is possible to visually check the etching processing state such as the presence or absence of stagnation of the etching solution 312 and to quickly determine whether or not the operating conditions related to the etching processing are appropriate. become.

FIG. 1 is a process flowchart for explaining an embodiment of the etching simulation method of the present invention. FIG. 2 is a plan view schematically showing an etching apparatus for performing an etching process on a copper substrate. FIG. 3 is a diagram schematically showing a process in which a cavity is formed in a local portion of a copper substrate by etching. FIG. 4 is a block diagram for explaining an embodiment of the etching / simulation apparatus of the present invention. FIG. 5 is a diagram illustrating an example of an image displayed on the output unit of the etching / simulation apparatus of the present invention. FIG. 5A shows the flow velocity distribution of the etching solution as an image, and FIG. 5B shows the cavity formed in the copper substrate as an image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Macro state calculation part 110 ... Macro state calculation condition setting means 120 ... Average liquid thickness calculation means 130 ... Nozzle locus calculation means 140-144 ... Spray amount distribution calculation means 150 ... Flow velocity distribution calculating means 160 ... Concentration distribution calculating means 170 ... Macro state quantity output means 200 ... Micro state calculating section 210 ... Micro state calculation condition setting means 220 ... Local flow velocity calculating means 230 ... Etching state quantity calculating means 240 ... micro state quantity output means 300 ... etching apparatus 301 ... nozzle 302 ... piping 303 ... copper substrate 304 ... arrow 305 ... spraying range 311 ... resist 312 ... etchant 313 ... arrow 314 ... cavity 315 ... side etch 400 ... etching stain Configuration device 410 ... input unit 420 ... processing unit 430 ... output section 431 ... image display means

Claims (8)

With respect to an etching process for forming a cavity in the substrate by transporting the substrate into an etching chamber provided with a plurality of nozzles for spraying an etching liquid, the flow rate of the etching liquid during the etching process and the etch rate of the cavity An etching simulation method for calculating an etch factor,
A macro state calculation unit for calculating a flow rate distribution of the etching solution on the substrate from the shape and driving design value related to the nozzle and the substrate, and a local flow rate of the etching solution near the cavity calculated separately;
From the flow velocity distribution calculated by the macro state calculation unit, the shape design value of the cavity, and the temperature and physical property value of the etchant, the etch rate and etch factor of the cavity formed at a predetermined position on the substrate And a micro state calculation unit that calculates the local flow rate of the etching solution in the vicinity of the cavity and outputs it to the macro state calculation unit,
An etching simulation method, wherein the flow rate distribution of the etching solution, the etch rate and the etch factor of the cavity are integrated and calculated. The macro state calculation unit
Based on the drive design value of the nozzle, average liquid thickness calculation means for calculating an average liquid thickness of the etching liquid on the substrate;
Nozzle trajectory calculation means for calculating the position and orientation of the nozzle based on the shape and drive design value of the nozzle;
A spray amount distribution calculating means for calculating a spray amount distribution on the substrate from the position and orientation of the nozzle calculated by the nozzle trajectory calculating means;
From the average liquid thickness calculated by the average liquid thickness calculation unit, the spray amount distribution calculated by the spray amount distribution calculation unit, and the local flow rate input from the micro state calculation unit, the flow rate of the etching liquid on the substrate A flow velocity distribution calculating means for calculating the distribution,
The micro state calculation unit
Local flow velocity calculation means for calculating the local flow velocity based on the average liquid thickness calculated by the average liquid thickness calculation means;
Etching state quantity calculating means for calculating the etch rate and etch factor of the cavity and the local concentration of the etching liquid and the waste liquid based on the local flow speed calculated by the local flow speed calculating means, The etching simulation method according to claim 1. Concentration distribution calculation for calculating the concentration distribution of the etching solution from the flow velocity distribution calculated by the flow velocity distribution calculation unit and the local concentration of the etching solution and the waste liquid in the vicinity of the cavity calculated by the etching state calculation unit. The etching simulation method according to claim 1, wherein means is added to the macro state calculation unit. The micro state calculation unit
A predetermined table in which the etch rate and the etch factor are set in advance using the local flow rate of the etching liquid, the shape design value of the cavity, and the etching processing time as parameters is provided in advance.
4. The etching simulation method according to claim 1, wherein an etching rate and an etching factor of the cavity are calculated based on the predetermined table. 5. The predetermined position on the substrate targeted by the micro state calculation unit is:
5. The etching simulation method according to claim 1, wherein the etching simulation method is any one point or two or more points on the substrate designated in advance. The predetermined position on the substrate targeted by the micro state calculation unit is:
5. The etching simulation method according to claim 1, wherein the etching simulation method includes all points on the substrate. An input unit for inputting the shape and drive design value of the substrate and the nozzle, the shape design value of the cavity, and the temperature and physical property value of the etching solution;
An arithmetic processing unit that performs a predetermined calculation according to the etching simulation method according to any one of claims 1 to 6,
An etching simulation apparatus comprising: an output unit that outputs a calculation result of the calculation processing unit. The output unit is
The etching simulation apparatus according to claim 7, further comprising an image display unit configured to image and display the flow velocity distribution and the etch factor calculated by the arithmetic processing unit.

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