JP7113507B2 - Active gas supply system and semiconductor manufacturing equipment using it - Google Patents

Description

The present invention can correct the gas flow rate in consideration of the active gas supply system such as hydrogen fluoride (hereinafter referred to as HF) used in the semiconductor manufacturing process, more specifically, the reaction amount of the active gas with the constituent materials of the semiconductor manufacturing apparatus. The present invention relates to a functional active gas supply system and a semiconductor manufacturing apparatus using the same.
In this specification, the term "reaction" includes not only chemical reaction but also adsorption, adhesion, and the like.

Active gases such as HF gas are used in various processing steps, such as etching processing of silicon oxide films in semiconductor manufacturing processes. In such a processing step, it is necessary to make the processing rate uniform in order to make the product quality uniform. control is taking place.

However, active gases, especially HF gas, are known to adsorb to and react with the surfaces of various metals. When the HF gas is consumed by the adsorption and reaction on the metal forming the inner wall of the processing chamber, even if the mass flow rate of the HF gas flowing into the processing chamber is precisely controlled, the mass of the HF gas used for the original processing is reduced. is decreased and the processing speed fluctuates. In particular, in the single-wafer processing of semiconductor substrates, the processing speed for the first few wafers of a processing lot may be lowered (for example, Patent Document 1).
This problem has become particularly apparent as the equipment has been required to be lighter so that it can be installed on the grating floor of semiconductor manufacturing plants, and chambers made of lighter metals such as aluminum have begun to be used in place of stainless steel. is becoming

In response to this problem, Patent Document 1 discloses that in order to reduce the adhesion of HF to the inner surface of the Al chamber, the surface oxidation treatment of Al on the inner surface of the chamber is abolished, and the surface roughness Ra of the Al is reduced. is proposed to be 6.4 μm or less.
As a result, it has been confirmed in HF sealing tests, actual flow tests, etc. that the amount of HF adsorbed to the chamber material has been reduced, and it has been reported that variations in the processing speed (etching speed) of semiconductor substrates have also been reduced. (Patent document 1).

Patent No. 4805948

As described above, Patent Document 1 points out problems such as the adsorption of HF gas to the metal material forming the inner wall of the processing chamber, and proposes an improvement in the surface treatment of the metal material as a countermeasure. It is a document that should be However, in order to apply this countermeasure to existing semiconductor manufacturing equipment, it is necessary to replace the chamber, etc., and the load is large.

The object of the present invention is to solve the above problems, consider the problem of active gas such as HF adsorbing or reacting to the inner wall of the chamber, and supply the active gas to the chamber so that the target active gas flow rate can always be obtained at the use point. To provide a system for correcting the flow rate of

A system of the present invention is a system for supplying an active gas to a chamber for processing a semiconductor substrate with the active gas,
A mass flow controller for controlling the supply amount of the active gas, a controller for controlling the mass flow controller, and a memory for storing an estimated reaction amount of the active gas with the inner wall of the chamber during processing of the semiconductor substrate. and
The controller is characterized by controlling the mass flow controller so as to correct the supply amount based on the estimated reaction amount during processing of the semiconductor substrate.

Preferably, the estimated reaction amount is set for each processing recipe and for each semiconductor substrate up to at least the first predetermined number of sheets in a processing lot, and the correction of the supply amount is performed for each processing recipe and each semiconductor substrate. Any configuration can be adopted.

Preferably, the estimated reaction amount is obtained in advance by at least one of a gas sealing test and an actual flow rate test,
In the gas sealing test, the chamber is filled with the target gas to create a sealed state, and the estimated reaction amount is obtained from the amount of pressure drop in the chamber when the chamber is left for a predetermined time,
In the actual flow rate test, the pressure rise per unit time in the chamber is measured when the valve on the downstream side of the chamber is closed and the target gas is allowed to flow into the chamber at a predetermined set flow rate by the mass flow controller. and the estimated reaction amount is obtained from the difference between the set flow rate and the actual flow rate,
configuration can be adopted.

Preferably, the system further includes a pressure gauge for measuring the pressure inside the chamber, and valves for opening and closing upstream and downstream sides of the chamber,
The controller controls the mass flow controller and the valve while reading the pressure gauge to measure the reaction amount, and performs at least one of the gas tightness test and the actual flow rate test. configuration can be adopted.

Preferably, a configuration can be adopted in which the active gas is HF gas.

A semiconductor manufacturing apparatus according to the present invention includes any one of the above systems.

According to the present invention, the controller controls the mass flow controller so as to correct the supply amount based on the estimated reaction amount during the processing of the semiconductor substrate, so that the target active gas flow rate can be obtained at the use point. be done.

It is a block diagram showing a system configuration of a 1st embodiment of the present invention. It is a table and a graph showing the results of the sealing test of the first embodiment of the present invention, (a) is SUS, (b) is material A, and (c) is a graph showing the results of material B. and (d) is a table summarizing the results. It is a table|surface which shows the result of the actual flow rate test of the 1st Embodiment of this invention. It is a block diagram which shows the system configuration|structure of the 2nd Embodiment of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
In the system of this embodiment, an operator manually obtains an estimated amount of reaction with the inner wall of the chamber in advance, and when processing a semiconductor substrate, the system uses HF gas, which is an active gas, based on this estimated amount of reaction. It corrects the supply amount of
FIG. 1 is a block diagram showing a first embodiment of the invention.
A system 100 of this embodiment includes a mass flow controller 1 , a controller 2 and a storage device 3 .

A mass flow controller 1 is connected to an HF supply source 4 through a gas supply system 5 and controls the mass flow rate of HF gas supplied to a downstream chamber 6 .
The controller 2 controls the operation of the mass flow controller 1 . The controller 2 does not need to be dedicated to this system, and may be one that controls part or all of the semiconductor manufacturing equipment, or may be a host computer that controls a plurality of semiconductor manufacturing equipment.
The storage device 3 stores an estimated amount of reaction of the active gas with the inner wall of the chamber 6 manually obtained in advance. The storage device 3 does not need to be dedicated to this system either.

The estimated reaction amount is the amount of gas consumed by adsorption on the inner wall of the chamber 6 per unit time, and the unit is sccm, which is the same as the mass flow rate. The estimated reaction amount is set for each processing recipe, and for at least the first five semiconductor substrates in a processing lot, for each substrate such as for the first substrate, for the second substrate, etc. For example, an estimated reaction amount table is set. saved as The reason for this is that, as will be described later, the amount of HF gas reacting with the inner wall of the chamber 6 is maximum immediately after the start of lot processing and tends to decrease sharply thereafter. This is because it changes depending on the order in which the substrate is processed in the lot. Also, the amount of reaction may vary depending on the processing conditions (HF gas flow rate, pressure, temperature, processing time, etc.) during substrate processing.

In the present embodiment, the estimated reaction amount is manually obtained by an operator in advance by performing at least one of a gas sealing test and an actual flow rate test, which will be described later, and stored in the storage device 3 . The save operation may be performed from the operation panel (not shown) of the controller 2 or through a communication line (not shown).

(Example)
Next, examples of the gas sealing test and the actual flow rate test are shown below.
In this embodiment, three types of chamber materials, stainless steel (SUS316L-EP), material A, and material B, were tested for comparison. A comparative test with _N2 gas was also conducted for validation ( _N2 supply line not shown).
As for the materials A and B, instead of actually fabricating the chamber from these materials, the materials A and B are placed in the chamber 6 made of stainless steel (hereinafter simply referred to as "SUS") which is considered not to react with the HF gas. A test piece was put in and the test was performed in a simulated manner.

(1) Gas Sealing Test (1.1) Procedure HF gas was introduced into the chamber 6, the pressure was set to 20 Torr (the temperature was set to 25°C), and the chamber 6 was filled with HF gas at a pressure of 20 Torr. Then, the chamber upstream valve V1 and the downstream valve V2 were closed and left for 2 hours, and the pressure inside the chamber was monitored with a pressure gauge P.
The pressure and temperature are preferably the same as those specified in the processing recipe. This is because the amount of reaction during testing is assumed to be the same as that during substrate processing.

(1.2) Results The results of the gas sealing test are shown in FIGS. 2(a) to 2(d).
First, in the SUS (no test piece in chamber 6), even if the pressure inside chamber 6 was left at 20 Torr for 2 hours in the N ₂ gas sealing test and the HF gas sealing test, the pressure in chamber 6 decreased by 0.11 at the maximum. Torr was hardly seen (Fig. 2(a)). This indicates that the N ₂ gas and HF gas hardly reacted with the inner wall of the SUS chamber 6 .
On the other hand, with material A and material B, almost no decrease was observed in the _N2 gas sealing test, but in the HF sealing test, a significant pressure drop of 18.1 Torr was observed for material A, and 1.89 Torr for material B. A Torr pressure drop was observed (FIGS. 2(b) and 2(c)). This is probably because the amount of HF gas reacting with the surfaces of the materials A and B was large during the sealing test, and as a result, the amount of HF present as gas in the chamber 6 decreased. Since the pressure curve in FIG. 2(b) drops sharply at the beginning and then settles down, the amount of reaction per hour between the HF gas and the material A was maximum at the start of the test, and then dropped sharply. it is conceivable that.

(1.3) Calculation of estimated reaction amount Gas change amount Δn (unit: mol), predetermined time Δt (unit: minute), pressure decrease amount ΔP (unit: ratio to 1 atmosphere) during that time, and From the volume V (unit: cc) and the absolute temperature T (unit: K) of the chamber 6, an estimated reaction amount Q (unit: sccm) per hour converted into flow rate is obtained by the following formula.
Q1=(Δn/Δt)·V ₀ =ΔP·V·273/(T·Δt)
The predetermined time Δt is preferably the same as the processing time of the HF processing of each semiconductor substrate specified in the processing recipe. For example, when the processing time is 1 minute, the predetermined time Δt is set to 1 minute, and the reaction amount Q1 from the start of the sealing test to 1 minute after the start is the estimated reaction amount during the processing of the first substrate. The reaction amount Q1 from 1 minute to 2 minutes is assumed to be the estimated reaction amount during the processing of the second substrate. This makes it possible to appropriately apply the estimated reaction amount, which is considered to be the maximum immediately after the start of processing of a lot and then rapidly decrease, to the processing of each semiconductor substrate.

(2) Actual flow rate test (build-up method)
(2.1) Procedure Closing the downstream valve V2 of the chamber 6, setting the set flow rate Q2 of the mass flow controller 1 to 300 sccm (set point 100%), allowing HF to flow into the chamber 6, and measuring the pressure rise with the pressure gauge P monitored by The amount of gas change Δn (unit: mol), the predetermined time Δt (unit: minute), the pressure rise ΔP (unit: ratio to 1 atm) during that time, the volume V (unit: cc) in the chamber 6, and the volume of the chamber 6 (unit: cc) From the absolute temperature T (unit: K), the actual flow rate Q3 (unit: sccm) was obtained by the following formula.
Q3=(Δn/Δt)·V ₀ =ΔP·V·273/(T·Δt)
This measurement was repeated five times without releasing the inside of the chamber 6 to atmospheric pressure.
The set flow rate Q2 and the initial pressure at this time are preferably the same as the flow rate and pressure of the HF gas specified in the processing recipe. This is because the amount of reaction during testing is assumed to be the same as that during substrate processing.

(2.2) Results Figure 3 shows the results of the actual flow rate test.
In the SUS (no test piece in chamber 6), even in the _N2 gas actual flow rate test and the HF gas actual flow rate test, the deviation of the actual flow rate Q3 from the set flow rate Q2 was small in all five times (in the _N2 gas actual flow rate test Maximum deviation of 0.02%, maximum deviation of 0.03% in HF gas actual flow rate test).
On the other hand, in the _N2 gas actual flow rate test, the deviation of the actual flow rate value from the flow rate setting value was as small as 0.07% for material A and material B, but in the HF gas actual flow rate test, the maximum deviation was 48.65 A very large deviation of 12.56% was observed at the minimum %, and a maximum deviation of 0.77% was observed on the negative side even under condition B.
This is probably because the HF gas reacted with or adhered to the surfaces of the materials A and B and was consumed, and as a result, the amount of HF present as gas in the chamber 6 decreased.
In addition, in the HF gas actual flow rate test, especially for material A, an extremely large deviation of 48.65% was observed on the negative side in the first measurement out of five repeated measurements, but the deviation narrowed as the number of times increased. did. The reason for this is probably that HF reacted or adhered during the first measurement and remained on the surface of the material A, preventing new reaction and adsorption of HF during the second and subsequent measurements.

(2.3) Calculation of estimated reaction amount The difference Q2-Q3 between the actual flow rate Q3 and the set flow rate Q2 is defined as the estimated reaction amount Q4.
Therefore, the sign-inverted value of the "error" in the table of FIG. 3 becomes the estimated reaction amount Q4.
The predetermined time .DELTA.t is preferably the same as the processing time of the HF processing for each semiconductor substrate. In that case, the estimated reaction amount Q4 obtained from the first measurement result is the estimated reaction amount during the processing of the first substrate, and the estimated reaction amount Q4 obtained from the second measurement result is the estimated reaction amount Q4 during the second substrate processing. can be assumed to be the estimated reaction amount. This makes it possible to appropriately apply the estimated reaction amount, which is considered to be the maximum immediately after the start of processing of a lot and then rapidly decrease, to the processing of each semiconductor substrate.

(3) Operation during semiconductor substrate processing The controller 2 reads the estimated reaction amount associated with the recipe to be executed and the semiconductor substrate to be processed from the estimated reaction amount table stored in the storage device 3, and reads the estimated reaction amount associated with the semiconductor substrate to be processed. Then, the flow rate obtained by adding the estimated reaction amount to the set flow rate designated by the recipe is instructed as a new set flow rate value. The mass flow controller 1 supplies HF gas to the chamber 6 based on this new flow rate setting.

(Second embodiment)
In the system of the present embodiment, the estimated reaction amount with the inner wall of the chamber 6 is automatically determined in advance, and the supply amount of HF gas is corrected based on this estimated reaction amount when processing the semiconductor substrate. be.

FIG. 4 is a block diagram showing the system of the second embodiment of the invention. In addition, the same code|symbol is attached|subjected to the component which is common in 1st Embodiment, and detailed description is abbreviate|omitted.
As shown in FIG. 4, the system 200 includes a mass flow controller 1, a controller 2, a storage device 3, a pressure gauge P, valves V1 and V2, and a displacement control valve V3.

The mass flow control device 1, the controller 2 and the storage device 3 are the same as those in the first embodiment, but the controller 2 further monitors the pressure of the pressure gauge P and controls the valves V1 and V2 and the displacement adjustment valve V3. controls the behavior of
The pressure gauge P measures the pressure inside the chamber 6 and outputs the measured pressure as data that the controller 2 can read.
The valves V1 and V2 are provided upstream and downstream of the chamber 6, respectively, and open and close the supply line and the exhaust line.
The exhaust amount adjustment valve V3 is provided between the chamber 6 and the exhaust system 7 to adjust the pressure in the chamber 6, and adjusts the exhaust amount from the chamber 6. As shown in FIG. However, if the valve V2 has a function of adjusting the displacement, the displacement adjustment valve V3 is not necessarily required.
It should be noted that the components and the signal lines connecting them may already be provided in the semiconductor manufacturing apparatus and used for normal semiconductor substrate processing.

Next, the operation of the system 200 of this embodiment configured in this manner will be described.
The operation of the system 200 of the present embodiment is similar to that of the system 100 of the first embodiment (see FIG. 1), except that at least one of the gas sealing test and the actual flow rate test is automatically performed by the controller 2 instead of manually. ) is the same as

(1) Gas sealing test The controller 2 controls each component to perform the following operations.
(1.1) Procedure HF gas is introduced into the chamber 6, the pressure is set to 20 Torr (the temperature is set to 25° C.), the chamber 6 is filled with HF at a pressure of 20 Torr, and the chamber upstream side valve V1 is closed. And the downstream side valve V2 is closed for 2 hours, and the pressure inside the chamber 6 is monitored with the pressure gauge P.
At this time, the pressure and temperature are set to be the same as the pressure and temperature during substrate processing specified in the processing recipe.

(1.2) Calculation of estimated reaction amount Gas change amount Δn (unit is mol), predetermined time Δt (unit is minute), pressure decrease amount ΔP (unit is ratio to 1 atmosphere) during that time, and chamber 6 From the volume V (unit: cc) and the absolute temperature T (unit: degree) of the chamber 6, an estimated reaction amount Q (unit: sccm) per hour converted into flow rate is obtained by the following formula.
Q1=(Δn/Δt)·V ₀ =ΔP·V·273/(T·t)
The predetermined time .DELTA.t is set to be the same as the processing time of the HF processing for each semiconductor substrate specified in the processing recipe. The reaction amount Q1 from the start of the sealing test to t after the start is assumed to be the estimated reaction amount during processing of the first substrate, and the reaction amount Q1 from t to 2 t after the start of the sealing test is assumed to be the estimated reaction amount during processing of the second substrate. do. In the same manner, the estimated reaction amount for each substrate processing is obtained and stored in the storage device 3 in association with the processing recipe.

(2) Actual flow rate test (build-up method)
The controller 2 controls each component to perform the following operations.
(2.1) Procedure Closing the downstream valve V2 of the chamber 6, setting the set flow rate Q2 of the mass flow controller 1 to 300 sccm (set point 100%), allowing HF to flow into the chamber 6, and measuring the pressure rise with the pressure gauge P to monitor. The amount of gas change Δn (unit: mol), the predetermined time Δt (unit: minute), the pressure rise ΔP (unit: ratio to 1 atm) during that time, the volume V (unit: cc) in the chamber 6, and the volume of the chamber 6 (unit: cc) From the absolute temperature T (unit: K), the actual flow rate Q3 (unit: sccm) is obtained by the following formula.
Q3=(Δn/Δt)·V ₀ =ΔP·V·273/(T·Δt)
This measurement is repeated five times without releasing the inside of the chamber 6 to atmospheric pressure.

(2.2) Calculation of estimated reaction amount The difference Q2-Q3 between the actual flow rate Q3 and the set flow rate Q2 is defined as the estimated reaction amount Q4.
The predetermined time Δt is set to be the same as the processing time of the HF processing for each semiconductor substrate. Then, the estimated reaction amount Q4 obtained from the first measurement result is the estimated reaction amount during the processing of the first substrate, and the estimated reaction amount Q4 obtained from the second measurement result is the estimated reaction amount Q4 during the processing of the second substrate. Estimated reaction volume.
In the same manner, the estimated reaction amount for each substrate processing is obtained and stored in the storage device 3 in association with the processing recipe.

(3) Operations During Semiconductor Substrate Processing As in the first embodiment, the controller 2 retrieves the estimated reaction amount table stored in the storage device 3, the recipe to be executed, and the estimated reaction associated with the semiconductor substrate to be processed. The amount is read, and the mass flow rate controller 1 is instructed as a new flow rate set value to be the flow rate obtained by adding this estimated reaction amount to the set flow rate designated by the recipe. The mass flow controller 1 supplies HF gas to the chamber 6 based on this new flow rate setting.

The present invention is not limited to the above-described embodiments, and those skilled in the art can make various additions and modifications within the scope of the present invention.
For example, in each of the above-described embodiments, the estimated reaction amount is set for each processing recipe and for each semiconductor substrate in a lot. A reaction amount may be set, an estimated reaction amount common to all recipes may be set for each substrate in a lot, or an estimated reaction amount common to all recipes and all substrates may be set.

Moreover, although the system of the second embodiment described above is capable of both the sealing test and the actual flow rate test, the present invention is not limited to this, and a system capable of performing only one of them may be used.

Further, in each of the above embodiments, the pressure, temperature, measurement time, etc. during the sealing test and the actual flow rate test were set according to the processing conditions specified in the processing recipe, but the present invention is not limited to this, and other suitable methods may be used. You can go under the conditions.

In each of the above-described embodiments, the estimated reaction amount during semiconductor substrate processing is used as the correction amount as it is. However, the present invention is not limited to this. For example, the estimated reaction amount multiplied by an appropriate coefficient may be used as the correction amount.

Reference Signs List 1: mass flow controller 2: controller 3: storage device 4: HF supply source 5: gas supply system 6: chamber 7: exhaust system 100: system 200 of the first embodiment: system P of the second embodiment: Pressure gauge T: Thermometer V1 to V2: Valve V3: Displacement control valve

Claims (6)

A system for supplying an active gas to a chamber for processing a semiconductor substrate with the active gas, comprising:
A mass flow controller for controlling the supply amount of the active gas, a controller for controlling the mass flow controller, and a memory for storing an estimated reaction amount of the active gas with the inner wall of the chamber during processing of the semiconductor substrate. and
The system, wherein the controller controls the mass flow controller so as to correct the supply amount based on the estimated reaction amount during processing of the semiconductor substrate. The estimated reaction amount is set for each processing recipe and for each semiconductor substrate up to at least the first predetermined number of sheets in a processing lot, and the supply amount is corrected for each processing recipe and for each semiconductor substrate; The system of claim 1. The estimated reaction amount is obtained in advance from at least one of the gas sealing test and the actual flow rate test,
In the gas sealing test, the chamber is filled with the target gas to create a sealed state, and the estimated reaction amount is obtained from the amount of pressure drop in the chamber when the chamber is left for a predetermined time,
In the actual flow rate test, the pressure rise per unit time in the chamber is measured when the valve on the downstream side of the chamber is closed and the target gas is allowed to flow into the chamber at a predetermined set flow rate by the mass flow controller. 3. The system according to claim 1 or 2, wherein the actual flow rate is obtained from the set flow rate and the estimated reaction amount is obtained from the difference between the set flow rate and the actual flow rate. further comprising a pressure gauge for measuring the pressure inside the chamber, and valves for opening and closing upstream and downstream sides of the chamber;
The controller controls the mass flow controller and the valve while reading the pressure gauge to measure the reaction amount, and performs at least one of the gas tightness test and the actual flow rate test. 4. The system of claim 3. A system according to any preceding claim, wherein the active gas is hydrogen fluoride gas. A semiconductor manufacturing apparatus comprising the system according to any one of claims 1 to 5.

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