JPS58115812A - Gas supply device for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To constantly maintain pressure in a reaction container with high accuracy while constantly maintaining the mixing ratio of each gas even when a plurality of gases are used by a method wherein correction amounts are calculated at eight or more stages for control. CONSTITUTION:Pressure P in a reaction container 5 is detected by a pressure sensor 7 and is fed into a comparator 8 to compare the pressure 7 with pressures P1,...P7 set with a setter 9 and correction amounts DELTAQ1-DELTAQ7 are supplied in accordance with each pressure range. The correction amounts DELTAQ1-DELTAQ7 are fed into an operator 10 and are multiplied between the feed ratio alphaa, alphab, alphac, of gases set with a setter 11 to divide proportionately into the correction amounts DELTAQa, DELTAQb, DELTAQc of each gas to add to a flow setter 4 and to perform flow correction. The sampling of the pressure 7 is done by applying timing pulses supplied by a timing generator 12 to the comparator 8.

Description

Detailed Description of the Invention (1) Technical Field of the Invention This invention relates to a gas supply device for semiconductor manufacturing equipment such as a CVD device, dry etching device, sputtering device, thermal oxidation or thermal nitridation device, etc. The present invention relates to a gas supply device that can stabilize the operation of a manufacturing device when manufacturing a semiconductor device.

(2) Prior art and problems Conventionally, in sputtering using a single gas, the gas pressure in the sputtering chamber was detected and the barrier pull leak valve was controlled by a servo mechanism.
A method of keeping the pressure inside the chamber constant was used, but when using multiple gases in various CVD, dry etching, reactive sputtering, thermal oxidation, thermal nitridation, etc. No method has been developed to keep the pressure constant through feedback techniques. A technique was used to maintain a constant flow rate. In this case, there are five problems in that the balance point with the inflow amount fluctuates due to fluctuations in the pumping speed of the pump that evacuates the reaction vessel, and the pressure inside the reaction vessel fluctuates.

Such pressure fluctuations greatly affect the reproducibility of semiconductor device characteristics, especially in plasma CVD using glow discharge.
The influence was remarkable in D, plasma etching, reactive sputtering, etc.

(8) Purpose of the Invention The purpose of the present invention is to maintain the pressure in the reaction vessel constant even in semiconductor manufacturing equipment that requires a plurality of gases as described above, and to not disturb the mixing ratio of each gas. The purpose of the present invention is to provide a gas supply device.

(4) Structure of the Invention The present invention includes a detector for detecting the pressure inside the reaction vessel, a setting device for setting a predetermined pressure, and a comparison between the values of the detector and the setting device, and depending on the deviation, the A comparator that calculates the correction amount in the steps above, a calculator that divides the correction amount into a predetermined flow rate ratio of multiple gases and applies correction to the mass 70-controller that controls the flow rate of each gas; This gas supply apparatus for manufacturing semiconductor devices is characterized in that it has an additional pressure control system consisting of a tie generator for controlling each element.

(ω) Embodiments of the invention FIGS. 1 and 2 show that in the present invention, the supply gas is
, C, and seven levels of correction amount. Each gas supply system includes a mass 70-detector 1
A conventional control system for maintaining the gas flow rate at the value set in the setting device 4 by means of the valve control circuit 2 and the barrier pull leak valve 8 is added. These three types of gases flow into the reaction vessel 6 and are simultaneously exhausted by the exhaust pump 6. The pressure inside the reaction volume 815 is determined by the balance between the gas inflow speed and the exhaust speed, and the pressure P is detected by the pressure sensor 7. be done. There are various types of pressure sensors, but a capacitance meter with a corrosion-resistant diaphragm is preferred because it meets the requirements for detecting absolute pressure and has high sensitivity and reliability.

The pressure value P detected by the pressure sensor enters the comparator 8, and the pressure value Pr, P set in the setting device 9 is input to the comparator 8.
g, Ps, ---Pt, each pressure cylinder i! 1ζζ
Correspondingly, correction amounts ΔQt to ΔQ1 are output. As shown in Figure 1112, the relationship between the pressure setting value and the correction amount is Δ below P1.
Let the correction amount be Q1, and the darkness of Pl and Pl is △Q・, Pg and P
The correction amount for s is ΔQi% between Ps and P4 and between P4 and Ps, ΔQs is between Pi and P, ΔQz is the difference between Ps and Pt, and ΔQ1 is the correction amount for Pt or more. Here, P
s-PyHAσΔQ1 to Δq1 vary depending on the controlled object, and it is necessary to set multiple values independently, but in this example, the values shown in the following table were used and good results were obtained. .

Note that a dead band in which the correction amount is zero in the range of Ps NPs is necessary to prevent hunting in the control system. Therefore, it is preferable that the number of correction stages is an odd number of 8 or more, and that the number of positive correction stages and the number of negative correction stages are equal. This is also possible if the control system has nonlinearity. Further, when the number of correction stages is two, it is difficult to perform high-precision control such as that used in semiconductor manufacturing equipment. Also, if there is non-linearity in the control system, the correction amount is ΔQl=-ΔQγ as shown in the chart.

ΔQ1=−ΔQJ1. In some cases, it is better not to set ΔQs=−ΔQFI.

The correction amounts ΔQ1 to △Q1 obtained as described above enter the calculator 10, and are multiplied by the flow rate ratios am, ab, and as of the three gases set in the setting W11, and the correction amounts △ Qa, △Qb.

It is added to the flow rate setter 4 of each gas control system in proportion to ΔQ6, and the flow rate correction is performed. Here, am
=Qa/(Qa+Qb+Qa).

ab=Qb/(Qa+Qb+Qs), ae-Q@/(
Qa+Qb+QI), and the subscripts a, b, of Q and α are
* represents the flow rate and flow rate ratio of gases A, B, and C, respectively.

In addition, sampling of pressure P was performed at 1111 when a tie occurred.
The timing pulse issued by comparator 8
This is done by adding to. The comparator 8 and the arithmetic unit 10 have a function of holding the respective correction amounts obtained there until the next sampling. Note that the sampling period may be determined based on [volume of reaction vessel]/[pumping speed]. In this example, the volume of 18j and 860
The sampling period is 8 seconds with an exhaust speed of 7/wim,
We are getting good results.

(6) Effects of the Invention According to the present invention, even when a plurality of gases are used, the pressure inside the reaction vessel can be kept constant with high precision while keeping the mixing ratio of each gas constant. If this gas supply device is used in CVD equipment, dry etching equipment, sputtering equipment, thermal oxidation/thermal nitridation equipment, etc., the operation of these equipment will become extremely stable, thereby greatly improving the reproducibility of the characteristics of manufactured semiconductor devices. do.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention. Here, 1 is a mass free detector, 2 is a valve control circuit, 8 is a barrier pull leak valve, 4 is a flow rate setting device, 6
1 is a reaction vessel, 6 is an exhaust pump, 7 is a pressure sensor, 8 is a comparator, 9 is a pressure setting device, 1G is a computing device, 11 is a flow ratio setting device, and 12 is a timing generator. Figure 1 Figure 2 Figure Q

Claims (1)

[Claims] In a gas supply apparatus having a plurality of gas supply systems to a reaction vessel for semiconductor device manufacturing, each of which is controlled in flow rate by a mass 70-controller, the pressure of the plurality of gas mixtures in the reaction vessel is controlled. a detector to detect;
A setting device that sets a predetermined value of the pressure in the reaction vessel, and a value obtained from the detector is compared with a value obtained from the setting device, and correction is made in eight or more steps according to the deviation. Pressure control comprising a comparator that calculates the amount, a computing unit that proportionally divides the correction amount into a predetermined flow rate ratio of the plurality of gases and applies correction to the mass flow controller, and a timing generator that controls each of the above components. A gas supply device for semiconductor device manufacturing, characterized in that a gas supply system is added thereto.