KR100642415B1 - Wafer processing reactor system with programmable processing parameters and method - Google Patents

Abstract

The present invention provides a wafer processing reactor system for processing a semiconductor wafer. The system includes a controller responsive to the steps of the recipe, each having a duration T _recipe , and controlling a plurality of process variables in the reactor. The controller provides a substantially gradual ramping of the process parameter values for a are formed to provide a control signal for changing the value of the process variable at a plurality of time intervals (T) is less than the duration T T _{recipe recipe.} The controller is also configured to allow the selection of the initial value, final value, and transition between values for the selected variable within the steps of the individual recipe.

Description

WAFER PROCESSING REACTOR SYSTEM WITH PROGRAMMABLE PROCESSING PARAMETERS AND METHOD

FIELD OF THE INVENTION The present invention relates generally to wafer processing reactor systems and, more particularly, to a reactor system for ramping selected process variables and a method of operation for providing repeatable control of a dynamic environment for processing wafers.

In the manufacture of semiconductors, wafer processing methods are used to deposit thin films on semiconductor substrates. Typically, chemical vapor deposition (CVD) methods are used, and recently plasma and high density plasma CVD (HDP-CVD) reactors and methods using the same are used to deposit thin films on small device microstructures. The plasma reactor can also be used for plasma etching. As an example, a process in a plasma reactor generally requires moving the wafer into the plasma chamber, exposing the wafer to a processing sequence, and removing the wafer from the chamber. The conditions of the processing chamber are different during wafer transfer rather than the processing process. In particular, plasma, high frequency power, gas flow, and vacuum pressure conditions are affected. The conditions are controlled to maintain a precise balance that ensures that the entire sequence is not interrupted and the desired results are produced on the wafer. Conditions that need to be carefully balanced include process gas flow, vacuum pressure, plasma high frequency power, chuck high frequency power, chuck clamping and gas pressure on the back of the wafer, etc. (collectively "process variables" or "variables"). Referred to as). These conditions affect the quality, stress, composition, etching, etc., and throughput of the thin film. Disruption of this balance of conditions leads to plasma loss, poor film quality, and wafer failure.

HDP-CVD techniques are useful in that they can fill narrow and deep gaps formed in semiconductor structures at relatively low temperatures (≦ 400 ° C.). Generally, the width of the gap is less than 0.35 micrometers and has an aspect ratio (ratio of height to width) of at least 2: 1. The gap is filled without voids by simultaneously depositing thin film material and sputtering the material at low speed so that the center of the gap is empty while filling the gap. The wafer temperature affected by plasma conditions and wafer loading and bias conditions has a significant impact on this deposition and sputtering rate.

Generally, wafer processing reactors and processes are controlled by a computer system. For example, in an HDP-CVD reactor control system, a user may use a process variable module (e.g., a high frequency and direct current power module, a vacuum system member, a gas mass flow controller, etc.) within a reactor and subsystem to process a given process. By defining variables, individual steps or states of the HDP-CVD process can be defined. This sequence of steps is considered a recipe. When the recipe is executed, the process variables are turned on and off via the variable module, which depends on the respective settings in each individual step. In general, process variables refer to electrical conditions, gases, and pressures within the processing chamber that must be balanced to produce a desired thin film result. However, in such a system, a change in the value of a variable can result in a step that is widely varied within the interval of the recipe step. 2 shows a general prior art recipe sequence consisting of N recipe steps. 2 shows that the values of the steps for two variables A and B change within the recipe sequence. In the prior art the user creates an individual fixed time length step with a setpoint for each individual process variable. A new step is required for each setpoint change, and each step operates for a specific period of time. That is, the recipe step is run for a fixed time duration and all setpoints are set at the beginning of the step and do not change until the next step is executed.

It is desirable to change the value of the process variable more abruptly and gradually than the recipe time step in a given step, or to change the value of the variable more quickly and gradually than the recipe time step, It is desirable to simultaneously change various variables with time steps.

Currently commercially available recipe software with time steps in seconds cannot provide a gradual change in the time steps in units equal to or less than the recipe time step. Therefore, another solution has to be found in fields such as HDP-CVD, in which ramping is required (at the same time) and within a shorter ramp time than seconds to maintain control of the reactor's environment and ensure repeatable processing results.

It is an object of the present invention to provide an improved wafer processing reactor system in which repeatable control of a dynamic environment for wafer processing is achieved.

It is yet another object of the present invention to provide a wafer processing reactor system configured to control the change of variable values gradually over a specific time interval.

It is yet another object of the present invention to provide a controller and method for controlling the processing characteristics of a reactor and the thin film characteristics of a wafer by gently and independently controlling one or more variables in the reactor.

It is a further object of the present invention to provide a wafer processing reactor comprising a controller which reduces the complexity for the user by minimizing the total number of steps in the process sequence or recipe.

It is yet another object of the present invention to provide a wafer processing reactor that provides smoothness and fine tuning of process parameters to achieve optimum thin film quality.

Thus, the controller is configured to control the plurality of process variables in the reactor according to the recipe step each having a duration T _recipe and to provide a control signal to change the value of the process variable in the plurality of time intervals T, where T is A wafer processing reactor system is provided for processing semiconductor wafers that are below the T _recipe and that provide substantially gentle ramping of the value of the process variable over the duration (T _recipe ).

Additional objects and features of the present invention will become more apparent from the following detailed description and claims, provided in conjunction with the drawings.

1 is a schematic diagram of a wafer processing reactor used in the present invention and describing certain process variable modules (e.g., mass flow gas input controllers, high frequency plasma and high frequency clamping chuck power modules, and vacuum system control);

2 is a schematic diagram showing gap filling in an HDP-CVD process,

3 shows a sequence of general recipes for two variables according to the prior art,

4 shows a sequence of general recipes for two variables in accordance with the present invention,

5 is a schematic diagram of a programmable controller according to one embodiment of the invention,

6 is a flow diagram for a sequence of predetermined programmable controls in accordance with one embodiment of the present invention;

7 shows a sequence of recipes according to Table 1,

8 is a table illustrating an embodiment of a sequence of recipes for operating an HDP-CVD reactor according to one embodiment of the present invention.

In order to better understand the present invention, a wafer processing system is shown in FIG. In an exemplary embodiment, the wafer processing system is a plasma reactor, in particular a high density plasma CVD reactor, although it is to be understood that the present invention may be used in any type of wafer processing system where repeatable control of a dynamic environment for wafer processing is desired. In FIG. 1, the reactor includes a plasma chamber 10 and a processing chamber 11. Chambers 10 and 11 are evacuated through port 12 to vacuum in the range of 0 to 20 mTorr via throttle valve 12a. The coil 13 is aligned around the plasma chamber 10 and excites the gas in the chamber into a plasma state when current is conducted at high frequency power. Various arrangements of coils or coils known in the art are used to generate the plasma. The substrate 16 is mounted on a support 17 (sometimes referred to as a chuck or electrostatic chuck) located in the processing chamber so that the surface of the substrate is facing upward. The support 17 is biased by application of a high frequency bias power through the high frequency generator 19 via the transmission line 21. Mechanical supports 17 or electrostatic supports known in the art are used to support the wafer. Support methods generally include means for providing pressurized gas (usually helium) between the support and the substrate to enable heat transfer from the substrate to the support. Helium gas is supplied through the mass flow controller 20 and the valve 21.

In FIG. 1 the gas may be injected into various different locations within the chamber. The gas may be injected into the top of the chamber through a gas inlet line 22 or an annular gas injector 34 located below the plasma source and on the substrate. The gas is premixed before entering the chamber as indicated by the mass flow controllers 25 and 26 and the valve 25a in the gas inlet line 22 or the mass flow controllers 31a and 31b and the gas inlet line 33b. May be Alternatively, the gas may be delivered as a single species as shown in connection with the mass flow controller 32 that transports a single gas through the gas inlet line 33a.

Generally, process gas enters the plasma chamber 10 via the gas inlet lines 33a and 33b via the process chamber 11 and / or the gas inlet line 22. High frequency power is applied to the coil 13 to decompose and ionize the gas (es). The predetermined gas flow rate is controlled by mass flow controllers 25, 26, 31a, 31b and 32, respectively.

In an exemplary embodiment, high frequency energy is supplied from the high frequency generator 28 to the chamber 10 through a coil 13 arranged around the chamber. In general, the frequency of high frequency energy is 13.56 MHz, which is a commercial standard frequency. In this configuration, a plasma is generated in the plasma chamber 10 by decomposing the percentage of gas molecules introduced by the first gas stream that includes ionized atoms to form reactive species. In a preferred embodiment of the present invention, an ion density of at least 10 ¹¹ ions / cm 3 is achieved, which is referred to as a high density plasma. The plasma contains electrons with very high energy compared to other species present. High energy electrons increase the decomposition density of reactive species that can be used for deposition or etching. While HDP-CVD reactors are disclosed, it is to be understood that the present invention may be practiced in various reactor forms, including etch reactors and CVD reactors. For example, gaseous chemistry of the second gas stream is introduced to provide deposition species. The deposition gas is introduced by the mass flow controllers 31a, 31b, and / or 32 at a predetermined selected flow rate. The gas is mixed in the gas inlet line 33b as it enters the processing chamber 11 or is directly transported via the gas inlet 33a. Gas injector 34 is mounted in the processing chamber adjacent the substrate to receive and disperse gas flow. Gas injector 34 includes a plurality of distribution holes (not shown) located equally around injector 34. The processing gas is distributed substantially uniformly around the surface of the substrate 16 through the distribution holes. The processing gas is decomposed and activated by the plasma flowing from the plasma chamber 10 into the processing chamber 11. In this degraded and activated state, the gas chemistry reacts to form a layer having a composition determined by the gas chemistry on the surface of the substrate 16. As mentioned above, the reactor accommodates a dynamic environment with multiple variables that are all balanced and time consuming to produce the desired wafer processing results.

The HDP-CVD technique allows for the filling of narrow deep gaps (typically <0.35 micrometers) formed in semiconductor structures having aspect ratios (height to width ratios) of at least 2: 1 at relatively low temperatures. 2 shows a typical structure with a gap. In order to completely fill the gap, it is important that the opening on the gap remains free of material until the bottom of the gap is filled. One approach deposits a small amount of material until the gap is filled, then sputters (or etches) a predetermined excess amount, and then deposits and sputters a larger amount of material. This alternating sequence is generally applied when the reactor's plasma density is limited (ie ≦ ^{10 10} ions / cm 3).

In a high density plasma apparatus, the plasma density is sufficiently high (ie, 10 ¹¹ ions / cm 3 or more) to simultaneously support deposition and sputtering. That is, a deposition gas is present to deposit the thin film and at the same time there is a sputter etching gas that sputter etches the thin film when the deposition gas is deposited. By controlling the sputtering power, gas flow and vacuum pressure, the deposition and sputtering rates can be controlled to fill the gaps more smoothly and more quickly than prior art devices. In general, in order to fill the gap completely, the sputtering rate and the deposition rate need to be changed when the gap is filled. In the early stages, the sputtering rate needs to be higher than when the gap is nearly filled. A substantially pure deposition step (ie, no sputtering component) may also be required to form the upper thin film on the gap. In order to ensure the best quality thin film and stable plasma in the reactor, the control of gas flow and power settings to manage the variation of sputtering and deposition rate should be done as gently as possible.

In addition, the deposition rate is very sensitive to the temperature of the wafer. For example, the deposition rate of silicon dioxide shows a change or sensitivity of about 10 Hz per change in temperature (° C.). Therefore, in a typical silicon dioxide thin film having a thickness of about 6000 GPa, in order to keep it uniformly within 3% of the entire wafer surface, the temperature of the wafer is 18 ° C. [calculated: ≦ 6000 × 0.3 (1/10 ° C.) = 18 ° C.]. The temperature of the wafer is affected by plasma power, gas composition, wafer holding force, sputtering (or bias) power, and gas pressure on the backside of the wafer. The gas flow, vacuum pressure, sputtering power required for the deposition / sputtering process as well as the equipment or variable modules controlling these elements must be adjusted in time and size relative to each other. To ensure the performance of large volumes and repeatable high quality thin films, the control of these variables must be automated. That is, it is highly desirable to provide repeatable control of the dynamic environment within the reactor to process wafers and form high quality thin films.

Control of the process in the reactor system is generally achieved through commercially available software. This software allows the user to define individual steps or states of the processing chamber and subsystems. By linking these steps together, the user creates a recipe that defines a sequence of gases, high frequency and direct current power modules, vacuum system members, and the like. When the recipe is executed, various variables are turned on and off via the variable module based on the settings in the individual steps. Many variables can be changed at each stage. However, in order to change the value of the variable over time using commercially available control software and prior art systems, the user is limited to a wide range of step changes with respect to the step interval of the recipe. The time of the step interval of a _recipe ("T _recipe ") is generally in units of 1 second or more. This means that if the user wishes to change the variable value gradually, the user is limited to the change in time step which is larger than the step of the recipe. If such a large, wide range of step changes is allowed, the user will know that many recipe steps are required to perform the recipe. In addition, the user can change various variables simultaneously, but may be limited to time steps larger than the time step of the recipe, and many recipe steps will be required. Managing and tracking the steps of many of these recipes is difficult.

In general, mass flow controllers and high frequency and direct current generators, pressure valves, pumps, etc., and combinations thereof (collectively referred to as "variable modules" or "process variable modules") are such units from a control computer operating a recipe. Controlled by sending a specific setpoint to the. The variable value is a selected process variable, such as mass flow rate in sccm, or the power value is wattage. At any stage of the recipe, any number of variables or process variables, i.e. the individual gases and voltages, can be varied within this time interval. However, the granularity of these time intervals is relatively rough compared to the deposition rate and acceptable thickness and plasma stability response time of the thin film. The change in the setpoint is limited by the length of the time step of the recipe, and the change in the setpoint occurs every hour in seconds. The resulting graph of this change would be like a staircase with very large steps as shown in FIG. 3 for the two gas variables A, B. These limitations make it difficult to control environmental conditions within the wafer processing reactors, and these results depend on very careful balance and time of conditions.

The inventors of the present invention have found that in certain applications it is desirable to change the variable value gradually and / or simultaneously for a time frame different from the time step (T _recipe ) of the _recipe . Gradual change refers to the change of the variable value from the initial value to the final value for a particular non-zero time window. In time T _early When changed to the T _end, X turns to the X _end the X _initial equation (X _final - X _initial) / (T _final - T _initial) = △ X / △ T indicates a predetermined change, △ T is the time of recipe The steps may be different. In a control design in which the device is mounted under computer control, it is gradually caused by converting the change in the variable value and the predetermined time interval into discrete step changes that are smaller than the predetermined total variable value change and the predetermined total time step change. Especially,

(x_i+1 - x_i) =

△x, 또는 (X_최종 - X_초기) = m△x 및(X _final -X _initial ) / m =

(x _{i + 1} -x _i ) =

Δx, or (X _final -X _initial ) = mΔx and

(T_j+1 - T_j) =

△t, 또는 (T_최종 - T_초기) = n△t이고(T _last -T _initial ) / n =

(T _{j + 1} -T _j ) =

Δt, or (T _last -T _initial ) = nΔt and

(X _Last -X _Initial ) / (T _Last -T _Initial ) = ΔX / ΔT = (m / n) (Δx / Δt) = k (Δx / Δt) and k is at time ΔT Is the number of steps of magnitude [Delta] x and [Delta] t that make a complete change [Delta] X

If k is large (Δx / Δt is small), the predetermined change from the initial variable to the final variable value and time draws a straight line. The limitation of straight or perfectly smooth changes is achieved when k approaches infinity.

In certain applications, such as HDP-CVD, it is necessary to achieve repeatable and careful control of the process environment, where the stability is determined by the complex balance of many variables. In this case the change in the variable value needs to be gradual. Preferably, the change in the variable value is gradual over a time interval that is shorter (or greater) than the time step of the recipe used in conventional software. That is, in order to balance the processing environment, a small Δx / Δt step should be applied and available to ensure a gradual and gentle change in the variable value when Δt <T _recipe .

The present invention utilizes the limitation of the recipe's time step (T _recipe ) in seconds, but adds the capability that the set point of the variable can change several times per second within the recipe's steps, thus providing a gentle over time interval of interest. Allows the formation of lines and steps with very small steps approaching smooth or gradual ramping. This is shown in Figure 4 illustrating the ramping control of the present invention and the relationship between ΔX and Δx and ΔT and Δt. Of particular advantages, the present invention utilizes a "smart device" which is a programmable electronic circuit between a system controller and a variable module. Alternatively, the smart device may be present in variable control. Wherever the circuit is physically present, the logic is the same. Smart devices are programmable electronic circuits that take input signals from the system controller and process the information and output signals in the calculated time sequence in the variable module. Such programmable electronic circuits preferably consist of commercially available programmable logic controllers (PLCs), but other suitable programmable electronic circuits such as computers based on rapid microprocessors may be used.

In particular, the conditions of the process chamber are set by variable modules such as mass flow controllers (MFCs), power sources, high frequency power generators, vacuum control, and the like. These variable modules operate independently of one another and in particular receive a single input value from the system controller to provide a single output value. For example, the MFC may be instructed to provide an output flow of 10 sccm, or the high frequency generator may be instructed to provide an output of 5000 watts. The variable module itself generally does not include the ability to accept and process instructions that change a value over time (ie, "lamp" up or down at the output). The response time of the variable module to a new input is generally not limited, i.e., a new command can be sent to the variable controller to provide a new output at frequencies above 60 Hz. The general limitation on the time between inputs is limited by what can be accommodated by commercially available variable modules, which are generally units of tens of milliseconds. Variable modules with a response time of 1 millisecond or less are commercially available and may be used in the present invention.

Referring again to FIG. 4, various different results of the present invention are shown. Although four recipe steps are shown in detail for variables A and B, it is to be understood that this is part of the recipe and the recipe can consist of N steps and M process variables. In general, portions 200, 201, 202 of the time curves of variables A and B are values ramped upwards and portions 203, 204 ramped downwards. Portion 200 is an example of variable A that is ramped for step (step 2) of the complete recipe and section 202 is ramped for part of step (step 3) and then remains constant for the rest of the steps. . Portion 201 shows the ramping of variable B between two recipe steps (steps 1 and 2). Portion 205 shows that variable B remains constant for all steps (step 3). In step 4 variable A in portion 204 ramps down at a different rate than variable B in portion 203. Finally, FIG. 3 shows that a step of a new recipe is started in each case where a new ramping condition is introduced. For example, variable A initiates a state change in steps 2, 3, and 4, while variable B initiates a state change in steps 1 and 4. The length of the time step of the recipe is different from one another, for example step 3 is longer than the other steps.

To obtain the ramping profile shown in FIG. 4, a controller according to the invention can be used as shown with reference to FIG. 5. The recipe enters the user interface computer 36 and is delivered to the controller 37. The controller 37 includes a system computer 38, and programmable electronic circuits 39. Programmable electronic circuit 39 is directly interfaced to variable module 40 representing a gas mass flow controller (MFC), a power source such as a high frequency generator and a direct current source, vacuum system control such as pumps and valves, and the like. The double arrow indicates that the information flow requires two directions for feedback and attestation. System computer 38 may include a commercially available microprocessor based computer. Preferably, system computer 38 is a VME computer. Programmable electronic circuit 39 may include electronic circuitry, which is a controller with programmable functionality, such as a rapid microprocessor based computer, a programmable logic controller (PLC), and the like. Preferably, the electronic circuit 39 is a commercially available PLC. In an alternative embodiment of the invention, programmable electronic circuit 39 may be present in each variable module 40, as opposed to a separate unit 39. If the programmable electronic circuitry is part of each variable module 40, the system computer 38 transmits an initial and final setpoint and ramp time to each individual variable module 40, including the smart device, each of which is Respond accordingly.

In accordance with the present invention, a user interface computer 36 comprising means for editing the steps of the recipe may include a ramp (ΔT) time, initial setpoint (X _initial ) from the initial setpoint to the final setpoint within the step of the recipe. And a function of specifying the _final setpoint (X _final ). Set points and times are stored as part of the recipe that runs within the reactor. It is possible to have one or more setpoints ramped simultaneously in a step of a given recipe. Each ramping setpoint in a step has its own specific ramping time, initial and final setpoints (ΔT, X _initial and X _final ).

When it is time for the recipe to run, the ramping setpoint is transferred from the user interface computer 36 to the controller 37. The controller 37 uses a system computer 38 and programmable electronic circuit 39 to facilitate the execution of the ramping recipe. The controller 37 is configured to process signals received from the user interface computer 36 and provide output control signals for controlling the process variable module 40. In particular, the system computer 38 receives the recipe from the user interface computer 36 and controls the execution of each step in the processing recipe. When the system computer 38 has a ramped recipe to be executed, the system computer 38 requests for a separate time step that is a ramping rate (ie, (X _last -X _initial ) / Δt), and a fixed Δt The number of steps k to be calculated is calculated and this information with the set point is transmitted to the programmable electronic circuit 39.

Among the particular advantages of the invention, the programmable electronic circuit 39 is selected to be a smart device, that is, the circuit is programmable and receives input from the system computer 38 to process information and receive signals in a calculated time sequence. Output to variable module 40. If programmable electronic circuit 39 has a setpoint and ramp rate, system computer 38 instructs programmable electronic circuit 39 to perform setpoint ramping. The programmable electronic circuit 39 can change the setpoint as quickly as the variable control 40 can accommodate, and generally this speed is chosen to provide the desired slope of the ramp rate, i. do. The time between changing set points is limited by the speed of the programmable electronic circuit, and can generally vary in the range of 1 second or less, and is as small as 1 millisecond or less. A time of Δt = 40 milliseconds is a typical value. A large number of time values can be selected, preferably time Δt is selected to meet the operational performance of the programmable electronic circuit, the variable module and the response time, and satisfies the requirements for ramping the wafer processing system. To be selected. In general, Δt is a single fixed value used with all variables, but this is not a requirement.

The system computer 38 monitors the progress of ramping and records the changed setpoints and substantial variables in the user interface computer 36. If a substantial predetermined value is out of range, it is completed during or after ramping, and the system computer 38 detects this condition and reports a warning or alert to the user interface computer 36. In the case of a warning condition, the system computer 38 takes appropriate measures to stop the execution of the ramping recipe and places the reactor in a safe, stable working condition.

The flowchart shown in FIG. 6 shows a computer program for practicing the present invention. Specifically, the user enters the recipe (ie, appropriate information such as the predetermined setpoint and time to be ramped) into the user interface computer 36 in step 102. The recipe is transferred to the system computer 38 present in the controller 37 in step 104. System computer 38 executes the steps of the recipe in step 106. If a query is made at step 108 and the steps of the recipe have been executed, the computer program ends at step 110. If the query determines that the step of the recipe has not been completed, the ramping decision is made at step 112. In step 112, a query is made as to whether the step of the recipe requires ramping. If positive, the program proceeds to step 114 where the system computer 38 calculates the ramp rate. If negative, the program returns to step 106.

When the system computer 38 calculates the ramping rate in step 114, the ramping rate Δx / Δt and the setpoint (X _initial , X _final ) are transferred to the programmable electronic circuit 39 in step 116. Send. Programmable electronic circuit 39 performs ramping in step 118. Ramping can change as quickly as variable control 40 responds. Step 120 executes the increment. The program executes step 122 when the setpoint changes, and the program queries whether the desired setpoint (ie, the setpoint introduced by the user) is equal to the _actual setpoint (X _actual ). If positive, the program returns to step 106 to continue execution of the step of the recipe. If negative, the program makes a change in step 124 to send this information to system computer 38. The program returns to step 118 and continues execution of this loop until the predetermined setpoint X _final is equal to the _actual setpoint X _actual .

The program evaluates if a warning condition exists. Referring back to FIG. 6, a comparison of the system computer in step 130 is made from the information received when the PLC executes ramping in step 118. The system computer 38 comparison is performed by asking if the value of the system computer is out of range in step 132. If affirmative, the warning condition is met at step 134 and the abort is executed at step 136. If negative, the program returns to step 130 to continue executing the system computer comparison.

The following is an operation example of the present invention shown in FIG. Process engineers want both gases to be ramped at different speeds within a given step. The process engineer states that the total step time is T _recipe = 30 seconds, and gas A flows in the user interface computer 36 from X _{initial A} = 0 to X _{final A} = 200 sccm at time ΔT _A = 3 seconds. And gas B flows from X _{initial B} = 0 to X _{final B} = 500 sccm at time DELTA T _B = 10 seconds. This data is transferred to the system computer 38. The programmable logic controller 39 receives the setpoint from the system computer 38 and calculates the ramping initial setpoint during the step by the equations for the gas flows A and B below.

Setpoint _new = setpoint _initial + [(X _last -X _initial ) / ΔT] * 0.04 * the number of steps, the number of steps being (1, 2, 3, ..., k). In the example, the time Δt of the step is assumed to be 40 milliseconds.

Table 1 provides new setpoint values for gases A and B at the selected stage.

Value for Example       Number of steps (k)        Time in seconds Set point of gas A (sccm) Set point of gas B (sccm)         0 0 ( _initial setpoint) 0 ( _initial setpoint)          One         0.040         2.67          2          2         0.080         5.33          4          3         0.120         7.99          6          4         0.160         10.64          8          25         1.00         66.7          50          50         2.00         133.3          100          75         3.00         200          150          100         4.00         200          200          125         5.00         200          250          250         10.00         200          500          500         20.00         200          500          750         30.00         200          500

Under this scheme, gas A will reach a complete setpoint after 3 seconds and continue to flow to the complete setpoint for the remaining 27 seconds of the step. Gas B, on the other hand, will continue to ramp when gas A stabilizes, reaching a complete setpoint in 10 seconds and maintaining this flow level for the remaining 20 seconds of this step. Ramping of the steps of the recipe lasts for 30 seconds and is shown in FIG.

An example of a gap fill recipe for forming a silicon dioxide thin film according to one embodiment of the present invention is shown in FIG. 8. The recipe consists of nine steps, and variable control 40, which can be set by the user, is shown in column A. FIG. In this example, the transition value or ramping time is determined by the silane (SiH ₄ ), argon, and oxygen flow rate, wafer backside gas pressure (“chuck helium” in FIG. 8), direct current power (“ESC voltage” and “in FIG. 8”). It is selected for chuck fixed voltage, plasma and chuck bias power (referred to as " chuck high frequency ramping time " and " plasma high frequency ramping time " in FIG. 8) controlled by ESC ramp time. Referring to step 5 in FIG. 8, three process variables, silane, argon and chuck high frequency power (ie, bias applied to the chuck) are ramped. The duration of step (5) is 9 seconds as indicated in the "Process time" column. As shown in step 5, in column 3, the flow rate of silane is ramped from 40 sccm (flow rate in the previous step 4) to 90 sccm at a ramp rate of 3 seconds (step 5, column 4). Reference]. At the same time argon is ramped from 120 sccm to 150 sccm after 2 seconds (shown in steps 5 and 6 and 7), and the bias power applied to the chuck to sputter is ramped from 0 to 1700 watts of bias power after 5 seconds. (Step 5, shown in columns 14 and 15). After step 5 is completed, these variables along with the oxygen and wafer back gas pressure are further ramped up in step 6 with a duration of 50 seconds.

If the ramping method of the present invention is not used, step 5 needs to be at least six steps, i.e. step 5 needs to be divided into six substeps, each of which is performed by the operator and You are asked to enter data that defines the substeps. That is, the sixth substep of executing the ramping rate and holding the step for four seconds to meet the nine seconds which is the total process time is executed. In particular, in the first two sub-steps the flow rate of silane is increased to 2/3 of the target value of 90 sccm, argon is completely 150 sccm, and the bias power is 2/5 of the target value of 1700 watts. The third substep transmits the silane to the target value, and the bias power may be increased by one and one fifth. The fourth and fifth substeps transmit the bias power completely to the target value (all other variables remain constant). The sixth substep keeps all variables constant for the remaining four seconds of the period of the original step (5). Each substep requires the operator to define the initial and final values of each variable. If the method of the invention is not possible, in contrast to the invention, which requires nine steps to carry out recipe (A), the entire recipe is instead of 1 + 1 + 4 + 3 + 6 + 11 + 10 + 4 + 4 = 44 steps (at least 1 second each).

Also, if the system and method of the present invention are not used, in addition to extending the recipe from nine steps to 44 steps, the transition for each variable change may be very sparse. For example, referring back to step 5 of FIG. 8, a predetermined change in silane gas flow from 40 sccm to 90 sccm after three seconds may occur in three steps of 16.6 sccm, ie 50 sccm / 3. This is a very coarse step change compared to the gradual step change achieved by the present invention, using a 40 millisecond time step which represents a partial step of 0.67 sccm in the example. Therefore, the systems and methods of the present invention not only minimize the number of recipes but also allow for a more gentle change of variable values over time than in the prior art.

Although the invention has been described with reference to some specific embodiments, the description is for the purpose of description and should not be construed as limiting the invention. Various modifications may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the claims.

Claims (25)

A wafer processing system for processing a semiconductor wafer, A controller for providing a control signal, The recipe step of the controller forms one or more transition durations that change one or more values for one or more process variables from an initial value to a final value that is different from the initial value, Wafer processing system. A wafer processing reactor system, A controller responsive to a plurality of recipe steps each having a duration T _recipe and controlling a plurality of process variables in the reactor, The controller is configured to provide a control signal for varying one or more values for one or more of the process variables from an initial value to a final value different from the initial value for a plurality of time intervals T less than a T _recipe . Wafer Processing Reactor System. The method of claim 2, The controller is configured to allow selection of initial values, final values, and time intervals T representing transitions between the initial and final values for the selected process variable within the individual recipe step, The controller, A system computer that receives the values and executes the recipe step by generating a ramping rate and one or more setpoints responsive to the values, and Programmable electronic circuitry for receiving said ramp rate and one or more set points from said system computer, And said programmable electronic circuit sends a control signal to said variable control responsive to said ramp rate and set point to provide substantially smooth ramping control of said process variable. The method of claim 2, And the system further comprises a user interface providing any one of the initial value, final value and time interval values. The method of claim 3, wherein And said programmable electronic circuitry is configured to change said set point as quickly as said variable control can receive a control signal. The method of claim 2, Wherein said variable control is selected from the group of mass flow controllers, high frequency generators, direct current generators, pressure valves, pumps, and combinations thereof. The method of claim 3, wherein And said system computer is a Virtual Memory Environment (VME) computer. The method of claim 2, The reactor is a wafer processing reactor system, characterized in that the chemical vapor deposition (CVD) reactor. The method of claim 2, And said reactor is an etching reactor. A wafer processing reactor system for processing semiconductor wafers in a chamber, A controller responsive to the recipe step to provide a control signal to the variable control, The controller is configured to allow selection of an initial value, a final value different from the initial value, a transition duration value between the initial value and the final value, for the selected variable within the individual recipe step, Wafer Processing Reactor System. The method of claim 10, The controller, A system computer that receives any one of the values and executes the recipe step by generating a ramping rate that changes the selected variable from the initial value to the final value, and one or more setpoints responsive to the values, and Programmable electronic circuitry to receive the ramp rate and one or more of the set points from the system computer, And said programmable electronic circuit transmits a control signal to said variable control responsive to said ramp rate and set point to provide substantially smooth control of process variables. The method of claim 10, The system further comprises a user interface providing any one of the initial value, final value and transition values. The method of claim 11, And said programmable electronic circuitry is configured to change said set point as quickly as said variable control is capable of receiving a control signal. The method of claim 10, The recipe step has a duration T _recipe , the transition duration between the initial value and the final value has a duration T, and T is shorter than the T _recipe. system. The method of claim 10, Wherein said variable control is selected from the group of mass flow controllers, high frequency generators, direct current generators, pressure valves, pumps, and combinations thereof. The method of claim 11, And said system computer is a virtual storage environment (VME) computer. The method of claim 10, The reactor is a wafer processing reactor system, characterized in that the chemical vapor deposition (CVD) reactor. The method of claim 10, The reactor is a wafer processing reactor system, characterized in that the high density plasma chemical vapor deposition (HDP CVD) reactor. The method of claim 11, And said programmable electronic circuit is a programmable logic controller. The method of claim 10, And said reactor is an etching reactor. A method of operating a wafer processing reactor having a process variable for processing a semiconductor wafer, _Defining one or more recipe steps with a duration T _recipe , In the one or more recipe steps, for at least one of the process variables, providing an initial value, a final value different from the initial value and a transition value between the values, wherein the transition is of short duration (T) than the T _recipe )-, According to said initial value, final value, and transition values within said one or more recipe steps, Providing an output signal comprising the ramping rate and at least the final value, and Operating the process variable in response to the output signal to process the semiconductor wafer Method of operating a wafer processing reactor comprising a. The method of claim 21, Wherein said process variable includes mass flow, pressure, direct current power, high frequency power, or a combination thereof. The method of claim 21, Wherein said process variable is executed simultaneously in individual recipe steps. The method of claim 21, And wherein the ramping rate is varied for each of the process variables within an individual recipe step. A method of depositing a layer on a surface of a semiconductor wafer in a plasma chemical vapor deposition reactor comprising a wafer support for supporting a wafer, a plasma chamber for generating a plasma, and a controller for receiving recipe steps, the method comprising: Applying high frequency power of a desired set value to the plasma chamber to generate the plasma, Clamping the wafer to the wafer support by applying a predetermined set of direct current power to the wafer support, Introducing a plurality of gases, each having a predetermined flow rate set value, into the reactor, Controlling the flow rate of the gas, direct current power and high frequency power in response to the recipe steps Including; The controller selects, for at least one of the flow rate, direct current and high frequency power set values, an initial value, a final value different from the initial value and a transition value between the initial value and the final value in one or more individual recipe steps. Formed to allow Wherein the flow rate, direct current and high frequency power setpoint values are ramped substantially gently to provide a deposition of a substantially uniform layer on the surface of the semiconductor wafer. A method of depositing a layer on the surface of a semiconductor wafer.

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