A high-precision flow regulating valve for semiconductor manufacturing

Abstract

The application discloses a high-precision flow regulating valve for semiconductor preparation, which comprises a driving mechanism for providing linear displacement driving force of a valve rod, the valve rod and a valve rod seat, the driving mechanism comprises a power assembly and a screw rod, the screw rod is sequentially provided with a fixed section, an outer thread section and a valve rod connecting section from top to bottom, the valve rod seat is sequentially provided with a first accommodating cavity and a second accommodating cavity which are mutually penetrated from top to bottom, the fixed section is connected to the power assembly through locking screws, the outer thread section is screwed with the inner thread of the first accommodating cavity, and the valve rod connecting section is located in the second accommodating cavity and connected to the connecting end of the valve rod; the matching gap between the outer thread section and the inner thread is 0.035mm-0.095mm, and the guiding length H of the valve rod connecting section in the second accommodating cavity is 11.3mm-13.5mm. The flow regulating valve guarantees the stability of the flow curve and reduces the flow deviation value during locking, and guarantees that the flow value deviation corresponding to each circle according to the scale is within ±10%.

Description

Technical Field

[0001] This invention relates to the field of valve technology, specifically to a high-precision flow control valve for semiconductor fabrication. Background Technology

[0002] In the mid-to-late 20th century, the rapid development of industries such as semiconductors, nuclear power, chemicals, and aerospace exposed fatal flaws in traditional packed needle valves: ① High risk of external leakage: The reciprocating motion of the valve stem leads to packing wear, aging, and weakening of clamping force, resulting in leakage of toxic, flammable, and high-purity media, polluting the environment, endangering safety, and affecting product purity; ② Poor adjustment accuracy: Lacking a precision positioning mechanism, the flow regulation is coarse, prone to drift, and not repeatable, failing to meet the requirements of high-purity and high-precision flow control; ③ Weak adaptability to operating conditions: The packing has low upper limits for temperature, pressure, and corrosion resistance, leading to rapid seal failure and short lifespan under high temperature, high pressure, strong corrosion, and high vacuum conditions; ④ High maintenance costs: Regular packing replacement and frequent maintenance are required, affecting continuous system operation.

[0003] In high-end industries, especially the semiconductor / microelectronics sector, gas delivery requires zero leakage, no particulate contamination, and ultra-high precision adjustment. Meanwhile, with the development of semiconductor technology, operating conditions are becoming increasingly complex. On the one hand, performance testing must include standard internal and external leakage, particle testing, and flow curve testing. On the other hand, testing is conducted under various extreme conditions, and standard performance requirements must be met during these tests. This necessitates comprehensive product verification through performance testing, cleanliness testing, long-term reliability testing, environmental adaptability testing, mechanical structure characteristic testing, fault injection testing, and packaging and transportation testing. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision flow control valve for semiconductor fabrication, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-precision flow control valve for semiconductor fabrication includes a drive mechanism providing linear displacement driving force for a valve stem, a valve stem, and a valve stem seat. The drive mechanism includes a power component and a lead screw. The lead screw has a fixed section, an external thread section, and a valve stem connecting section arranged sequentially from top to bottom. The valve stem seat has a first receiving cavity and a second receiving cavity arranged sequentially from top to bottom, which are mutually communicating. The fixed section is abutted against the power component by a locking screw. The external thread section is screwed into the internal thread of the first receiving cavity. The valve stem connecting section is located in the second receiving cavity and is connected to the connecting end of the valve stem. The mating clearance between the external thread section and the internal thread is 0.035 mm to 0.095 mm. In the second receiving cavity, the guide length H of the valve stem connecting section is 11.3 mm to 13.5 mm, and the single-sided installation clearance of the guide section is 0.01 mm to 0.02 mm. mm, wherein the guide length is the vertical length of the contact section between the lower part of the valve stem connecting section and the inner sidewall of the second receiving cavity; the single-sided installation gap between the valve stem seat and the lead screw is 0.3 mm to 0.5 mm.

[0007] Furthermore, the valve stem connecting section is a cylindrical structure with an open bottom. The valve stem connecting section is composed of a frustum conical section and a cylindrical section arranged sequentially from top to bottom. The shape of the second receiving cavity is adapted to the outer contour shape of the valve stem connecting section so that when the valve stem connecting section rises to the top in the second receiving cavity, its top wall is completely in contact with the top wall of the second receiving cavity. The connecting end of the valve stem extends into the inner cavity of the valve stem connecting section.

[0008] Furthermore, the lead screw also includes a transition section located between the external thread section and the valve stem connecting section, wherein the diameter of the external thread section is greater than the diameter of the fixed section and the transition section and smaller than the outer diameter of the valve stem connecting section; at least a portion of the transition section moves up and down within the first receiving cavity and the second receiving cavity.

[0009] Furthermore, the power assembly includes a rotating handle with a bottom-open receiving cavity and a graduated ring. The fixed section extends into the receiving cavity, and the two are coaxially arranged. The fixed section is detachably connected directly or indirectly by a locking bolt perpendicular to its axial direction. The upper part of the valve stem seat extends into the lower inner part of the rotating handle, and the graduated ring is sleeved on the upper part of the valve stem seat. The upper part of the graduated ring is located between the rotating handle and the valve stem seat, and the graduated ring is connected to the outer wall of the valve stem seat.

[0010] Furthermore, a bushing ring is fitted around the outside of the fixed section, and the rotating handle is detachably connected to the bushing ring and the bushing ring to the fixed section by locking screws perpendicular to the lead screw axis; the scale ring is detachably connected to the outer wall of the valve stem seat by locking screws perpendicular to the lead screw axis.

[0011] Furthermore, the valve stem seat also includes a third receiving cavity located below the second receiving cavity. The high-precision flow control valve for semiconductor fabrication also includes a bellows sleeved on the metering section of the valve stem and a mother body with an inlet and an outlet. The mother body is located below the valve stem seat and is connected to each other. The mother body has a valve stem receiving cavity for accommodating the lower part of the valve stem. The metering section of the valve stem extends from the third receiving cavity to the valve stem receiving cavity. The bellows is located in the third receiving cavity. The upper end of the bellows is connected to the valve stem, and the lower end is connected to the top surface of the mother body.

[0012] Furthermore, a convex frustum section is provided between the connecting section of the valve stem and the metering section. The top end of the bellows is fixedly connected to the bottom surface of the convex frustum section, and a bellows welding ring is connected to the bottom end of the bellows. The bellows welding ring is connected to the top surface of the mother body.

[0013] Furthermore, the flow control valve also includes a steel ball placed at the top of the valve stem, the top of which abuts against the top wall of the cylindrical inner cavity of the valve stem connecting section.

[0014] Furthermore, the top wall of the cylindrical inner cavity of the valve stem connecting section is a conical surface, and a conical groove is provided at the top of the valve stem, with the steel ball being engaged between the top wall of the cylindrical inner cavity and the conical groove.

[0015] Furthermore, the valve stem is connected to the lead screw via a pin, and the main body and the valve stem seat are connected via a clamping nut.

[0016] The high-precision flow control valve for semiconductor fabrication of the present invention reduces the tilt angle of the lead screw by coordinating the guide length and the thread fit clearance between the lead screw and the valve stem seat, thereby reducing the impact on the valve stem and thus reducing the impact on the flow rate. This ensures a stable flow curve and reduces the flow deviation value during locking, ensuring that the flow value deviation corresponding to each revolution of the scale is within ±10%.

[0017] High-precision flow regulation must ensure: ① stability of the zero position; ② consistency of the flow area under different opening degrees during use.

[0018] To ensure the above two points, after the machining accuracy of the parts meets the given requirements (i.e., the valve stem taper and orifice size tolerance), the hardness of the raw materials needs to be specified. At the same time, the valve stem and the base body are surface hardened to increase hardness and prevent wear during contact. Due to its small valve stem taper, there will be a small flow gap at the zero position to prevent damage to the parts, with a basic flow rate (10-15 sccm@10psig). In this case, when adjusted to the zero position, by installing a bushing ring, the bottom of the bushing ring contacts the upper part of the valve stem seat, which becomes the mechanical limit of the valve. At this time, the contact between the valve stem and the base body is non-contact or light contact. Due to the increased hardness of the contact parts, no wear will occur under this condition, thus ensuring the stability of the zero position.

[0019] To ensure that the valve stem and the valve body are in light contact when zeroing, i.e., the force during contact does not cause wear, the lead screw is guided as much as possible when it contacts the valve stem seat. At the same time, the rotational motion is converted into linear reciprocating motion by steel balls. The valve stem and the bellows form a bellows welded assembly. At this time, the valve stem is in a non-guided state. Through the control measures during assembly, the valve stem is automatically centered when closed to the zero position.

[0020] The dynamic particle performance of the flow control valve (testing the number of particles inside the valve during the process of opening from zero to maximum opening and then closing back to zero) is related to the relative movement of its valve stem and orifice. The present invention, through the good guidance of the lead screw, transmits the information to the valve stem, and the valve stem adapts at the orifice to form a light contact, so that wear will not be reached during multiple operations, that is, no large number of particles will be generated, thereby achieving high cleanliness. Attached Figure Description

[0021] Figure 1 This is a longitudinal section of the high-precision flow control valve for semiconductor fabrication described in this invention. Figure 1 .

[0022] Figure 2 This is a longitudinal section of the high-precision flow control valve for semiconductor fabrication described in this invention. Figure 2 .

[0023] Figure 3 This is a perspective view of the high-precision flow control valve for semiconductor fabrication described in this invention.

[0024] Figure 4 The flow coefficient curves of valve 1 and valve 2 described in Example 1 are compared.

[0025] Figure 5 The flow coefficient curves for valves 9 to 17 described in Example 1 are shown.

[0026] Among them, 1-valve stem, 2-valve stem seat, 3-lead screw, 4-locking screw, 5-rotating handle, 6-scale ring, 7-bulb ring, 8-bellows, 9-mother body, 10-steel ball, 14-compression nut, 15-bellows welding ring, 11-connecting section, 12-metering section, 13-outer convex frustum section, 21-first receiving cavity, 22-second receiving cavity, 23-third receiving cavity, 31-fixed section, 32-external thread section, 33-valve stem connecting section, 331-conical frustum section, 332-cylindrical section, 91-inlet, 92-outlet. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] like Figures 1-2 As shown, the present invention provides a high-precision flow control valve for semiconductor fabrication, comprising a drive mechanism providing linear displacement driving force for the valve stem, a valve stem 1, and a valve stem seat 2. The drive mechanism includes a power assembly and a lead screw 3. The lead screw 3 is provided with a fixed section 31, an external thread section 32, and a valve stem connecting section 33 from top to bottom. The valve stem seat 2 is provided with a first receiving cavity 21 and a second receiving cavity 22 that are mutually connected from top to bottom. The fixed section 31 is abutted to the power assembly by a locking screw 4. The external thread section 32 is screwed to the internal thread of the first receiving cavity 21. The valve stem connecting section... 33 is located within the second receiving cavity 22 and connected to the connecting end of the valve stem 1; the mating clearance between the external thread section 32 and the internal thread is 0.035~0.095mm; within the second receiving cavity 22, the guide length H of the valve stem connecting section 33 is 11.3mm~13.5mm, and the single-sided installation clearance of the guide section is 0.01-0.02mm, wherein the guide length is the vertical length of the contact section between the lower part of the valve stem connecting section and the inner sidewall of the second receiving cavity; the single-sided installation clearance between the valve stem seat and the lead screw is 0.25mm~0.4mm.

[0029] The valve stem connecting section 33 is a cylindrical structure with an open bottom. The valve stem connecting section 33 is composed of a frustum conical section 331 and a cylindrical section 332 arranged sequentially from top to bottom. The shape of the second receiving cavity 22 is adapted to the outer contour shape of the valve stem connecting section 33 so that when the valve stem connecting section 33 rises to the top in the second receiving cavity 22, its top wall is completely in contact with the top wall of the second receiving cavity 22. The connecting end of the valve stem 1 extends into the inner cavity of the valve stem connecting section 33.

[0030] Furthermore, the lead screw 3 also includes a transition section located between the external thread section 32 and the valve stem connecting section 33. The diameter of the external thread section 32 is larger than the diameter of the fixed section 31 and the transition section and smaller than the outer diameter of the valve stem connecting section 33. At least a portion of the transition section moves up and down within the first receiving cavity 21 and the second receiving cavity 22.

[0031] The power assembly includes a rotating handle 5 with a bottom open receiving cavity and a scale ring 6. The fixed section 31 extends into the receiving cavity, and the two are coaxially arranged. The fixed section 31 is detachably connected directly or indirectly by a locking screw 4 perpendicular to its axial direction. The upper part of the valve stem seat 2 extends into the lower inner part of the rotating handle 5. The scale ring 6 is sleeved on the upper part of the valve stem seat 2. The upper part of the scale ring 6 is located between the rotating handle 5 and the valve stem seat 2. The scale ring 6 is connected to the outer wall of the valve stem seat 2.

[0032] Furthermore, a bushing ring 7 is fitted around the outside of the fixed section 31. The rotating handle 5 is detachably connected to the bushing ring 7 and the bushing ring 7 is detachably connected to the fixed section 31 by locking screws 4 perpendicular to the axis of the lead screw 3. The scale ring is detachably connected to the outer wall of the valve stem seat 2 by locking screws 4 perpendicular to the axis of the lead screw 3.

[0033] The valve stem seat 2 further includes a third receiving cavity 23 located below the second receiving cavity 22. The high-precision flow control valve for semiconductor fabrication also includes a bellows 8 sleeved on the metering section of the valve stem 1 and a mother body 9 having an inlet 91 and an outlet 92. The mother body 9 is positioned below the valve stem seat 2 and connected to it. The mother body 9 has a valve stem receiving cavity for accommodating the lower part of the valve stem 1. The metering section of the valve stem 1 extends from the third receiving cavity 23 to the valve stem receiving cavity. The bellows 8 is located within the third receiving cavity 23. The upper end of the bellows 8 is connected to the valve stem 1, and the lower end is connected to the top surface of the mother body 9. Specifically, the valve stem 1 is connected to the lead screw 3 via a pin; the mother body 9 and the valve stem seat 2 are connected via a clamping nut 14.

[0034] A convex frustum section 13 is provided between the connecting section 11 of the valve stem 1 and the metering section 12. The top end of the bellows 8 is fixedly connected to the bottom surface of the convex frustum section 13. A bellows welding ring 15 is connected to the bottom end of the bellows 8. The bellows welding ring 15 is connected to the top surface of the mother body 9.

[0035] The flow control valve also includes a steel ball 10 placed at the top of the valve stem 1. The top of the steel ball 10 abuts against the top wall of the cylindrical inner cavity of the valve stem connecting section 33. The top wall of the cylindrical inner cavity of the valve stem connecting section 33 is a conical surface. A conical groove is provided at the top of the valve stem 1. The steel ball 10 is engaged between the top wall of the cylindrical inner cavity and the conical groove.

[0036] Comparative Example 1

[0037] In this embodiment, two flow control valves were selected. The guide length of the two flow control valves is 8.13mm (when closed to zero position)-11.3mm (when opened to the point where the lower part of the lead screw is entirely within the guide section). The fit clearance between the external thread section and the internal thread is 0.1mm. The clearance between the bellows and the valve stem seat is 1.5mm. The zero position of the valve stem is located at the arc corner. The valve stem and the body have not undergone hardening treatment.

[0038] First, the flow accuracy of the two valves was tested at an intake pressure of 30 psig. The zero-point flow rate and flow rate per revolution of valve 1 and valve 2 are shown in Table 1, and the CV value per revolution of valve 1 and valve 2 are shown in Table 2. The flow curves of valve 1 and valve 2 are shown in Table 2. Figure 4 As shown, based on the test data above, it can be seen that the flow curves of the two valves are abnormally adjusted, the flow coefficient curves are non-linearly increasing, and a sudden change in flow occurs in the first cycle.

[0039] Table 1

[0040]

[0041] Table 2

[0042]

[0043] In addition, three valves identical to valves 1 and 2 were selected, and their locking function was tested at an intake pressure of 30 psig (the flow rate changes during locking were measured, and the names were not changed). Table 3 shows the flow rate of the three valves in the locked and unlocked states at different opening turns, and Table 4 shows the flow rate change rate of the three valves in the locked and unlocked states at different opening turns. The analysis showed that the flow rate change rate of the three valves in the locked and unlocked states at opening turns of 1 to 3 was 1.49%-6.79%.

[0044] Table 3

[0045]

[0046] Table 4

[0047]

[0048] Three valves identical to valve 1 were selected for zero-position (internal leakage) performance testing. The results are shown in Table 5. The internal leakage performance of the three valves was unstable, failing to achieve 10-15 sccm@10psig; it was either too high or too low. Dynamic particle performance testing was then conducted on these three valves. The particle test requirements were: ≥0.1µm particles: ≤7.07 ptc / L (ptc: particles), (200 particles / 28.3L). The test results are shown in Table 6. The results show that the dynamic particle leakage of this valve structure with ≥0.1µm particles was 27-34.2 ptc / L, which is seriously excessive.

[0049] Table 5

[0050]

[0051] Table 6

[0052]

[0053] Example 1

[0054] This embodiment first selected nine flow control valves of the present invention. The mating clearance between the external thread section and the internal thread of the nine flow control valves is 0.035 mm to 0.095 mm. Its structure ensures that the guide length of the lead screw is 11.3 mm throughout the entire opening stroke, and the single-sided installation clearance of the guide section is 0.01-0.02 mm. Its limit is precisely controlled on the conical surface and 1 mm away from the root of the arc. The single-sided installation clearance between the bellows and the valve stem seat is precisely controlled between 0.125 mm and 0.2 mm, which can effectively reduce the clearance while ensuring that the outer diameter expansion during compression will not contact the outer wall, thus affecting the service life. At the same time, the valve stem and the body are subjected to surface hardening treatment to improve the surface hardness. The flow accuracy of the nine valves was tested under an intake pressure of 30 psig. The zero-point flow rate and flow rate per revolution test results of the nine valves are shown in Table 7, the CV value per revolution of the nine valves are shown in Table 8, and the flow curves of the nine valves are shown in Table 9. Figure 5 As shown, based on the test data above, the flow curves of the nine valves rise uniformly, and the deviation value of each revolution is within ±10%.

[0055] Table 7

[0056]

[0057] Table 8

[0058]

[0059] Then, the zero-position (internal leakage) performance of the above 9 valves was tested. The test results are shown in Table 9. As can be seen from the table, the zero position of the 9 valves is stable at 10-15 sccm@10psig.

[0060] Table 9

[0061]

[0062] Finally, dynamic particle performance tests were conducted on the above nine valves. The particle test requirements were: ≥0.1µm particles: ≤7.07ptc / L (ptc: particles), (200 particles / 28.3L). The test results are shown in Table 10. The results show that the dynamic particle performance of this valve structure is ≥0.1µm particles 0-3.63 ptc / L, which is good and has been greatly improved.

[0063] Table 10

[0064]

[0065] In addition, three identical valves from the aforementioned nine valves were selected. First, at an intake pressure of 30 psig, the flow rate variation per revolution of the three valves was tested, along with a locking function test. Table 11 shows the flow rate of the three valves in the locked and unlocked states at different opening revolutions, and Table 12 shows the flow rate variation rate of the three valves in the locked and unlocked states at different opening revolutions. Analysis showed that the flow rate variation rate of the three valves in the locked and unlocked states at opening revolutions of 1 to 3 was 0.37%–1.51%.

[0066] Table 11

[0067]

[0068] Table 12

[0069]

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision flow control valve for semiconductor fabrication, comprising a drive mechanism providing linear displacement driving force for a valve stem, a valve stem, and a valve stem seat, wherein the drive mechanism includes a power component and a lead screw, characterized in that, The lead screw is provided with a fixed section, an external thread section, and a valve stem connecting section from top to bottom. The valve stem seat is provided with a first receiving cavity and a second receiving cavity that are interconnected from top to bottom. The fixed section is abutted to the power assembly by a locking screw. The external thread section is screwed to the internal thread of the first receiving cavity. The valve stem connecting section is located in the second receiving cavity and is connected to the connecting end of the valve stem. The fit clearance between the external thread section and the internal thread is 0.035 mm to 0.095 mm. In the second receiving cavity, the guide length H of the valve stem connecting section is 11.3 mm to 13.5 mm. The single-sided installation clearance of the guide section is 0.01 mm to 0.02 mm. The guide length is the vertical length of the contact section between the lower part of the valve stem connecting section and the inner sidewall of the second receiving cavity. The single-sided installation clearance between the valve stem seat and the lead screw is 0.3 mm to 0.5 mm.

2. The high-precision flow control valve for semiconductor fabrication according to claim 1, characterized in that, The valve stem connecting section is a cylindrical structure with an open bottom. The valve stem connecting section is composed of a frustum conical section and a cylindrical section arranged sequentially from top to bottom. The shape of the second receiving cavity is adapted to the outer contour shape of the valve stem connecting section so that when the valve stem connecting section rises to the top in the second receiving cavity, its top wall is completely in contact with the top wall of the second receiving cavity. The connecting end of the valve stem extends into the inner cavity of the valve stem connecting section.

3. The high-precision flow control valve for semiconductor fabrication according to claim 2, characterized in that, The lead screw also includes a transition section located between the external thread section and the valve stem connecting section. The diameter of the external thread section is greater than the diameter of the fixed section and the transition section and smaller than the outer diameter of the valve stem connecting section. At least a portion of the transition section moves up and down within the first receiving cavity and the second receiving cavity.

4. A high-precision flow control valve for semiconductor fabrication according to claim 1, characterized in that, The power assembly includes a rotating handle with a bottom-open receiving cavity and a graduated ring. The fixed section extends into the receiving cavity, and the two are coaxially arranged. The fixed section is detachably connected directly or indirectly by a locking bolt perpendicular to its axial direction. The upper part of the valve stem seat extends into the lower inner part of the rotating handle, and the graduated ring is sleeved on the upper part of the valve stem seat. The upper part of the graduated ring is located between the rotating handle and the valve stem seat, and the graduated ring is connected to the outer wall of the valve stem seat.

5. A high-precision flow control valve for semiconductor fabrication according to claim 4, characterized in that, A bushing ring is fitted around the outside of the fixed section. The rotating handle is detachably connected to the bushing ring and the bushing ring is detachably connected to the fixed section by locking screws perpendicular to the lead screw axis. The scale ring is detachably connected to the outer wall of the valve stem seat by locking screws perpendicular to the lead screw axis.

6. A high-precision flow control valve for semiconductor fabrication according to claim 2, characterized in that, The valve stem seat also includes a third receiving cavity located below the second receiving cavity. The high-precision flow control valve for semiconductor fabrication also includes a bellows sleeved on the metering section of the valve stem and a mother body with an inlet and an outlet. The mother body is located below the valve stem seat and is connected to each other. The mother body has a valve stem receiving cavity for accommodating the lower part of the valve stem. The metering section of the valve stem extends from the third receiving cavity to the valve stem receiving cavity. The bellows is located in the third receiving cavity. The upper end of the bellows is connected to the valve stem, and the lower end is connected to the top surface of the mother body.

7. A high-precision flow control valve for semiconductor fabrication according to claim 6, characterized in that, A convex frustum section is provided between the connecting section of the valve stem and the metering section. The top end of the bellows is fixedly connected to the bottom surface of the convex frustum section. A bellows welding ring is connected to the bottom end of the bellows, and the bellows welding ring is connected to the top surface of the mother body.

8. A high-precision flow control valve for semiconductor fabrication according to claim 6, characterized in that, The flow control valve also includes a steel ball placed at the top of the valve stem, the top of which abuts against the top wall of the cylindrical inner cavity of the valve stem connecting section.

9. A high-precision flow control valve for semiconductor fabrication according to claim 8, characterized in that, The top wall of the cylindrical inner cavity of the valve stem connecting section is a conical surface, and a conical groove is provided at the top of the valve stem. The steel ball is stuck between the top wall of the cylindrical inner cavity and the conical groove.

10. A high-precision flow control valve for semiconductor fabrication according to claim 6, characterized in that, The valve stem is connected to the lead screw via a pin, and the valve body and the valve stem seat are connected via a clamping nut; both the valve stem and the valve body undergo surface hardening treatment.

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