ALD (atomic layer deposition) process combined type temperature control method

Abstract

The invention relates to an ALD (atomic layer deposition) process combined type temperature control method which comprises the following steps: S1, heating to a first-stage set temperature at a full speed, so that the heating time can be effectively shortened; s2, the temperature is increased to the set temperature of the second stage in a buffering mode through accumulated heat, and temperature overshoot can be effectively reduced; and S3, PID temperature control is adjusted to the final set temperature, and the oscillation time of PID can be effectively shortened. Preferably, the method comprises the step S4 of feeding back and adjusting the set temperature values of the first stage and the second stage and the output power of the second stage according to data collected in the temperature control process, namely a temperature control result. And the temperature control continuously tends to be idealized. The method has the advantages that the heating time can be effectively shortened due to full-speed heating in the first half section, the temperature overshoot can be effectively reduced due to low-power heating in the middle section and continuous temperature rise and release of stored heat due to heat storage, the oscillation time of PID can be effectively shortened due to the fact that PID is started near the set temperature, and temperature control can continuously tend to idealization due to feedback and parameter self-adjustment in each heating process.

Description

Technical Field

[0001] The present invention relates to an ALD process composite temperature control method, belonging to the technical field of photovoltaic ALD. Background Art

[0002] In the ALD process, the process of each furnace material needs to be carried out at a specific temperature. Therefore, the furnace temperature needs to be raised to the process temperature before the process and kept stable throughout the process.

[0003] In the prior art, PID temperature control is usually used for heating control. Since the heat dissipation in the vacuum furnace chamber is slow, it takes a long time for the temperature to fall back after overshooting, resulting in a longer time for the temperature to stabilize. Therefore, in practical applications, efforts are made to slow down the oscillation of the PID curve, or to lower the first cycle oscillation to below the set temperature. However, this process will also cause the power output to be lowered during the entire PID process, and will also prolong the heating time. Summary of the invention

[0004] The present invention proposes a composite temperature control method for an ALD process, the purpose of which is to overcome the above-mentioned deficiencies in the prior art, reduce temperature overshoot, and shorten the heating time.

[0005] The technical solution of the present invention is a composite temperature control method for an ALD process, comprising the following steps:

[0006] S1, heating at full speed to the first stage set temperature, which can effectively shorten the heating time;

[0007] S2, relying on the accumulated heat to buffer the temperature to the second stage set temperature, which can effectively reduce temperature overshoot;

[0008] S3, PID temperature control is adjusted to the final set temperature, which can effectively shorten the PID oscillation time.

[0009] Preferably, the method further comprises step S4, wherein the set temperature values ​​of the first and second stages and the output power of the second stage are adjusted based on the data collected during the temperature control process, i.e., the temperature control result, so that the temperature control can be continuously improved to an ideal state.

[0010] Preferably, the step S1 specifically includes: first reading the preset first stage set temperature T 1 , and then compare it with the current feedback temperature T. If T <T 1 , the output Q is 100%, and the heating rod outputs at maximum power until the current feedback temperature T≥T 1 .

[0011] Preferably, the step S2 specifically includes: reading the preset second stage set temperature T 2 , where T 2>T 1 , then T 2 Compared with the current feedback temperature T, if T <T 2 , the output Q maintains low power output, the output value Q L The device continues to heat up to T by relying on the heat storage in the first stage of heating. 2 During this process, the device will release some of the stored heat. At the same time, due to the low power output, the temperature of the heating rod will also drop to a suitable temperature control range.

[0012] Preferably, the step S3 specifically includes: reading the final set temperature T of the device 3 , T 3 >T 2 , then enable PID control and set T 3 As the target value of PID control, the control output of PID is used as output Q, so that the temperature is finally constant at the final set temperature T 3 superior.

[0013] Preferably, the output of the PID is:

[0014]

[0015] Among them, T 3 Indicates the set temperature, K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of PID control respectively, and Q(t) represents the output of PID control.

[0016] Preferably, in step S4, during the heating process, the following data are collected:

[0017] The duration of the second stage 2 ,

[0018] The third stage temperature overshoot ΔT 3 ,

[0019] The third stage temperature stabilization process duration t 3 ,

[0020] Average output Q after temperature stabilization in the third stage A ,

[0021] During the third stage of temperature stabilization, the output overshoot ΔQ 3 ;

[0022] According to the above collected data, feedback is used to adjust the control parameters of each stage as follows:

[0023] Adjust the first stage set temperature:

[0024] T 1 =T' 1 +A 1 t 2 -A 2 ΔT 3 -A 3 t 3

[0025] Among them, T' 1 is the original first stage set temperature, A 1 , A 2 , A 3 is the preset adjustment factor;

[0026] Adjust the second stage set temperature:

[0027] T 2 =T' 2 +A 4 ΔT 3 +A 5 ΔQ 3

[0028] Among them, T' 2 is the original second stage set temperature, A 4 , A 5 is the preset adjustment factor;

[0029] Adjust the second stage output power:

[0030] Q L =Q' L +A 6 (Q A -Q' L )

[0031] Among them, Q' L is the original second stage set output power, A 6 is the preset adjustment factor;

[0032] The adjusted control parameters are used as the parameters for the next heating and temperature control.

[0033] The advantages of the present invention are: the method is reasonably designed, specific,

[0034] 1) Full speed heating in the first half can effectively shorten the heating time;

[0035] 2) Low-power heating in the middle section, which continues to heat up by storing heat and releases the stored heat, which can effectively reduce temperature overshoot;

[0036] 3) Starting the PID near the set temperature can effectively shorten the PID oscillation time;

[0037] 4) Each heating process provides feedback and self-adjusts parameters, which can make the temperature control continuously approach the ideal. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of the ALD process composite temperature control method of the present invention.

[0039] Figure 2 This is a diagram of the temperature variation of the bottom plate heating according to an embodiment of the present invention.

[0040] Figure 3 It is a temperature variation diagram of the bottom plate of the comparative example of the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below with reference to examples and specific implementation modes.

[0042] like Figure 1 As shown, a composite temperature control method for an ALD process comprises the following steps:

[0043] S1, heating at full speed to the first stage set temperature:

[0044] First read the preset first stage set temperature T 1 . Then compare it with the current feedback temperature T. If T <T 1 , the output Q is 100%, and the heating rod outputs at maximum power until the current feedback temperature T≥T 1 .

[0045] S2, rely on the accumulated heat to buffer and raise the temperature to the second stage set temperature:

[0046] Read the preset second stage set temperature T 2 , where T 2 >T 1 Then T 2 Compared with the current feedback temperature T, if T <T 2 , the output Q maintains low power output, the output value Q L is the preset power value. The equipment continues to heat up to T by relying on the heat stored in the first stage of heating. 2 During this process, the device will release some of the stored heat. At the same time, due to the low power output, the temperature of the heating rod will also drop to a suitable temperature control range.

[0047] S3, PID temperature control is adjusted to the final set temperature:

[0048] Read the final set temperature T of the device 3 , where T 3 >T 2 Then enable PID control and set T 3As the target value of PID control, the control output of PID is used as output Q, so that the temperature is finally constant at the final set temperature T 3 superior.

[0049] Output of P ID:

[0050]

[0051] Among them, T 3 Indicates the set temperature, K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of PID control respectively, and Q(t) represents the output of PID control.

[0052] S4. According to the temperature control results (data collected during the temperature control process), feedback is provided to adjust the set temperature values ​​of the first and second stages and the output power of the second stage:

[0053] During the heating process, the following data are collected:

[0054] 1. Duration of the second stage t 2 ;

[0055] 2. Temperature overshoot ΔT in the third stage 3 ;

[0056] 3. Duration of the third stage temperature stabilization process t 3 ;

[0057] 4. Average output Q after temperature stabilization in the third stage A ;

[0058] 5. During the third stage of temperature stabilization, the output overshoot ΔQ 3 .

[0059] According to the above collected data, feedback is used to adjust the control parameters of each stage as follows:

[0060] Adjust the first stage set temperature:

[0061] T 1 =T' 1 +A 1 t 2 -A 2 ΔT 3 -A 3 t 3

[0062] Among them, T' 1 is the original first stage set temperature, A 1 , A 2 , A 3 is the preset adjustment factor.

[0063] Adjust the second stage set temperature:

[0064] T 2 =T' 2 +A 4 ΔT 3 +A 5 ΔQ 3

[0065] Among them, T' 2 is the original second stage set temperature, A 4 , A 5 is the preset adjustment factor.

[0066] Adjust the second stage output power:

[0067] Q L =Q' L +A 6 (Q A -Q' L )

[0068] Among them, Q' L is the original second stage set output power, A 6 is the preset adjustment factor.

[0069] In the above formula, the adjustment coefficient is obtained by experiment.

[0070] The adjusted control parameters will be used as the parameters for the next heating and temperature control.

[0071] Example

[0072] like Figure 2 As shown, the composite heating method of the present invention is adopted. The starting point of the curve corresponding to the heating rod in the figure corresponds to S1, the highest interval corresponds to S2, and the subsequent section of the highest interval corresponds to S3. The maximum set temperature of the heating rod is 700°C, the actual maximum temperature is 700°C, and it lasts for 3 minutes. It takes about 28 minutes to heat the bottom plate to 150°C.

[0073] Comparative Example

[0074] like Figure 3 As shown, the existing full-process PID heating method is adopted, the maximum setting temperature of the heating rod is 700°C, due to the automatic suppression function of the PID, the actual maximum temperature is about 650°C, and the bottom plate temperature is heated to 150°C, which takes about 1 hour and 20 minutes.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A composite temperature control method for an ALD process, characterized in that: It includes the following steps: S1. Heat at full speed to the set temperature of the first stage, which can effectively shorten the heating time; S2. Buffer the temperature rise to the set temperature of the second stage by the stored heat, which can effectively reduce the temperature overshoot; S3. Adjust the temperature by PID control to the final set temperature, which can effectively shorten the oscillation time of PID.

2. The ALD process composite temperature control method according to claim 1, characterized in that: It also includes step S4. According to the data collected during the temperature control process, i.e., the temperature control result, feedback and adjust the set temperature values of the first stage and the second stage and the output power of the second stage.

3. A composite temperature control method for an ALD process according to claim 1 or 2, characterized in that: The specific step S1 is as follows: First, read the preset set temperature T1 of the first stage, then compare it with the currently feedback temperature T. If T < T1, the output Q is 100%, and the heating rod outputs at the maximum power until the currently feedback temperature T ≥ T1.

4. The ALD process composite temperature control method according to claim 3, characterized in that: The specific steps of step S2 are as follows: read the preset set temperature T2 in the second stage, where T2 > T1, and then compare T2 with the currently feedback temperature T. If T < T2, the output Q maintains a low-power output, and the output value Q L is the preset power value, and the device continues to heat up to T2 by relying on the heat storage during the first-stage heating process.

5. The ALD process composite temperature control method according to claim 4, characterized in that: The specific step S3 is as follows: Read the final set temperature T3 of the device, T3 > T2, then enable PID control, use T3 as the target value of PID control, and the control output of PID as the output Q, so that the temperature is finally constant at the final set temperature T3.

6. The ALD process composite temperature control method according to claim 5, characterized in that: The output of the said PID: E(t)=T3(t)-T(t) Where, T3 represents the set temperature, K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of PID control respectively, and Q(t) represents the output of PID control.

7. The ALD process composite temperature control method according to claim 6, characterized in that: In step S4 during the heating process, collect the following data: The duration t2 of the second stage, The temperature overshoot ΔT3 of the third stage, The duration t3 of the temperature stabilization process of the third stage, Average output Q after temperature stabilization in the third stage A , During the temperature stabilization process of the third stage, the output overshoot ΔQ3; According to the above collected data, feedback and adjust the control parameters of each stage as follows: Adjust the set temperature of the first stage: T1 = T’1 + A1t2 - A2ΔT3 - A3t3 where, T’1 is the original set temperature of the first stage, and A1, A2, A3 are preset adjustment coefficients; Adjust the set temperature of the second stage: T2 = T’2 + A4ΔT3 + A5ΔQ3 where, T’2 is the original set temperature of the second stage, and A4, A5 are preset adjustment coefficients; Adjust the output power of the second stage: Q L =Q’ L +A6(Q A -Q’ L ) Among them, Q' L It is the original second stage set output power, A6 is the preset adjustment coefficient; the adjusted control parameters are used as the parameters for the next heating temperature control.

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