Airflow-adjustable etching machine and etching method

Abstract

The invention discloses an airflow-adjustable etching machine. The airflow-adjustable etching machine comprises a reaction chamber, a nozzle, a wafer carrying table and an airflow control system, the airflow control system comprises a first airflow baffle ring; the first airflow baffle ring is arranged in the reaction chamber and is positioned between the nozzle and the wafer carrying table; the first airflow baffle ring is arranged in the reaction chamber and located between the nozzle and the wafer carrying table, and a vent hole is formed in the position, opposite to the nozzle, of the first airflow baffle ring. According to the scheme, the first airflow baffle ring is arranged, airflow is gathered to the position above the wafer towards the center, the airflow can react with the wafer more directly, and the etching uniformity is improved. The invention further discloses an etching method using the etching machine capable of adjusting the airflow.

Description

Technical Field

[0001] The invention relates to the technical field of etching machines, and in particular to an etcher with adjustable airflow and an etching method. Background Art

[0002] Plasma etcher, also called plasma plane etcher, plasma etcher, plasma surface treatment instrument or plasma cleaning system, is used in the semiconductor industry. Inductively coupled plasma etching is the result of the interaction of chemical and physical processes. Its basic principle is that under vacuum and low pressure, the radio frequency generated by the ICP radio frequency power supply is output to the annular coupling coil, and a certain proportion of mixed etching gas is coupled to glow discharge to generate high-density plasma. Under the action of the RF radio frequency of the lower electrode, these plasmas bombard the surface of the substrate, and the chemical bonds of the semiconductor in the graphic area of ​​the substrate are broken, and volatile substances are generated with the etching gas, which are separated from the substrate in the form of gas and are extracted from the vacuum pipeline.

[0003] In etching equipment, the wafer needs to be sprayed with air during the process. Different areas of the wafer will be sprayed with air in a downward and tilted direction. Generally, the existing spray structures cannot be adjusted or have limitations in adjustment, and the RF coil is also fixed, so when the etching uniformity is poor, there will be no significant improvement.

[0004] At present, due to the limitations of the overall structure, the plasma density and distribution of plasma etcher are uneven, and the airflow is scattered in various places in the chamber, resulting in poor etching uniformity of wafers. Since the RF structures such as plasma coupling coils and air nozzles are fixed, the uniformity cannot be greatly improved. Taking metal aluminum etching as an example, the uniformity of metal aluminum etchers on the market is generally above 8%. In addition, the airflow is dispersed and not concentrated, and part of the airflow is directly pumped away by the pump, resulting in unnecessary waste. Summary of the invention

[0005] In view of this, the present invention provides an etcher with adjustable gas flow to solve the technical problem of poor uniformity of existing etchers.

[0006] The present invention also provides an etching method using the etcher with the adjustable gas flow.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] An etcher with adjustable airflow comprises: a reaction chamber, a nozzle, a wafer carrier and an airflow control system; the airflow control system comprises: a first airflow baffle ring; the first airflow baffle ring is arranged in the reaction chamber and located between the nozzle and the wafer carrier; a vent hole is provided at a position opposite to the nozzle of the first airflow baffle ring.

[0009] Preferably, the first airflow baffle ring is a circular ring, the outer diameter of which matches the inner diameter of the chamber liner in the reaction chamber, and a gap is left between the outer circle of the first airflow baffle ring and the chamber liner to prevent particle aggregation.

[0010] Preferably, the airflow control system further comprises: a first lifting device; the first lifting device can make the first airflow baffle ring move up and down.

[0011] Preferably, the first lifting mechanism comprises: a first lifting drive and a first transmission mechanism; the first transmission mechanism is located between the wafer carrier and the reaction chamber; and the first lifting drive is arranged outside the reaction chamber.

[0012] Preferably, the first transmission mechanism includes: a first baffle ring lifting rod and a first guide sleeve; the first end of the first baffle ring lifting rod is connected to the first airflow baffle ring, and the second end of the first baffle ring lifting rod is connected to the first lifting drive; the middle part of the first baffle ring lifting rod is arranged in the first guide sleeve, and the first guide sleeve is arranged on the inner surface of the chamber substrate in the reaction chamber, and is located between the wafer carrier and the reaction chamber.

[0013] Preferably, the first transmission mechanism also includes: a first adjusting block and a first fixed seat; the first end of the first baffle ring lifting rod is connected to the first end face of the first adjusting block through the first adjusting block screw, the second end face of the first adjusting block is connected to the first airflow baffle ring through the first fixing screw, and the second end of the first baffle ring rod is connected to the first lifting drive through the first fixed seat.

[0014] Preferably, the airflow control system further comprises: a stacked baffle ring; the outer circle of the stacked baffle ring is detachably mounted on the inner circle of the first airflow baffle ring.

[0015] Preferably, the number of the stacked baffle rings is multiple, with inner and outer arrangements. The outer circle of the inner stacked baffle ring can be detachably mounted on the inner circle of the outer stacked baffle ring, and the outer circle of the outermost stacked baffle ring can be detachably mounted on the inner circle of the first airflow baffle ring.

[0016] Preferably, the inner diameter of the first airflow baffle ring is 120% of the wafer diameter, and the inner diameter of the innermost stacked baffle ring is 80% of the wafer diameter.

[0017] Preferably, the airflow control system also includes: a second airflow baffle ring; the second airflow baffle ring is arranged between the wafer carrier and the reaction chamber, and is located below the first airflow baffle ring, and an annular air passage is formed between the outer circle of the second airflow baffle ring and the reaction chamber.

[0018] Preferably, the second airflow baffle ring is a circular ring coaxial with the wafer stage, and the inner diameter thereof matches the outer diameter of the wafer stage.

[0019] Preferably, the airflow control system further comprises: a second lifting device; the second lifting device can make the second airflow baffle ring move up and down.

[0020] Preferably, the second lifting device comprises: a second lifting drive and a second transmission mechanism; the second transmission mechanism is located between the wafer carrier and the reaction chamber; and the second lifting drive is arranged outside the reaction chamber.

[0021] Preferably, the second transmission mechanism includes: a second baffle ring lifting rod and a second guide sleeve; the first end of the second baffle ring lifting rod is connected to the second airflow baffle ring, and the second end of the second baffle ring lifting rod is connected to the second lifting drive; the middle part of the second baffle ring lifting rod is arranged in the second guide sleeve, and the second guide sleeve is arranged on the inner substrate surface of the chamber in the reaction chamber, and is located between the wafer carrier and the reaction chamber.

[0022] Preferably, the second transmission mechanism also includes: a second adjusting block and a second fixed seat; the first end of the second baffle ring lifting rod is connected to the first end face of the second adjusting block through a second adjusting block screw, the second end face of the second adjusting block is connected to the second airflow baffle ring through a second fixing screw, and the second end of the second baffle ring lifting rod is connected to the second lifting drive through the second fixed seat.

[0023] Preferably, a height difference between the first airflow baffle ring and the second airflow baffle ring is 20-70 mm.

[0024] An etching method, using the above-mentioned etcher with adjustable gas flow, comprises the steps of:

[0025] S1, sequentially forming a SiO2 insulating layer and an Al layer on a semiconductor substrate;

[0026] S2, setting the airflow control system, including: adjusting the diameter of the vent hole;

[0027] S3, etching the Al layer.

[0028] Preferably, the setting of the airflow control system further includes: adjusting the height difference between the first airflow baffle ring and the second airflow baffle ring.

[0029] Preferably, before setting the airflow control system, the method further comprises: obtaining the optimal values ​​of the vent hole diameter and the height difference, comprising the steps of:

[0030] The height difference remains unchanged, the etching rate uniformity under different vent hole diameters is obtained, and the vent hole diameter corresponding to the optimal etching rate uniformity is obtained by comparison;

[0031] The vent hole diameter corresponding to the optimal etching rate uniformity remains unchanged, the etching rate uniformity under different height differences is obtained, and the height difference corresponding to the optimal etching rate uniformity is obtained by comparison.

[0032] Preferably, obtaining the optimal values ​​of the vent hole diameter and the height difference comprises:

[0033] The diameter of the vent hole is set to 220 mm, and the uniformity of the etching rate when the height difference is 20, 30, 40 and 50 mm is obtained, and the height difference corresponding to the optimal uniformity of the etching rate is obtained by comparison;

[0034] The height difference is set to 30 mm, and the etching rate uniformity is obtained when the vent hole diameters are 210, 220 and 230 mm respectively, and the vent hole diameters corresponding to the optimal etching rate uniformity are obtained by comparison.

[0035] It can be seen from the above technical solutions that the etcher with adjustable gas flow provided by the present invention gathers the plasma gas by setting the first gas flow baffle ring, thereby solving the technical problem of poor uniformity of the etcher;

[0036] The etching machine can also meet the requirements of different processes by detachably installing a superimposed baffle ring on the inner circle of the first airflow baffle ring, without the need to disassemble and replace the first airflow baffle ring;

[0037] The etcher further improves uniformity by adjusting the height difference between the first airflow baffle ring and the second airflow baffle ring;

[0038] The present invention also provides an etching method. Since the above-mentioned etcher with adjustable airflow is adopted, it also has corresponding beneficial effects. For details, please refer to the above description, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the overall structure of an etcher with adjustable gas flow provided in an embodiment of the present invention;

[0041] Figure 2A schematic structural diagram of a chamber of an etcher with adjustable gas flow provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the airflow direction of an etcher with adjustable airflow provided in an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of a partially enlarged structure of a chamber of an etcher with adjustable gas flow provided in an embodiment of the present invention;

[0044] Figure 5 It is a schematic diagram of the airflow direction (before flow control) of the prior art;

[0045] Figure 6 A schematic diagram of the airflow direction (after flow control) of an etcher with adjustable airflow provided in an embodiment of the present invention;

[0046] Figure 7 A schematic diagram of a method for improving uniformity of an etcher with adjustable gas flow provided in an embodiment of the present invention;

[0047] Figure 8 The 8-inch uniformity comparison diagram under different inner diameters with a height difference of 30 mm provided in Example 1 of the present invention;

[0048] Fig. 9 The 8-inch uniformity comparison diagram under different height differences with an inner diameter of 220 mm provided in Example 2 of the present invention;

[0049] Fig.10 The 6-inch uniformity comparison diagram under different inner diameters with a height difference of 30 mm provided in Example 3 of the present invention.

[0050] Among them, 101-reaction chamber, 102-lower cylinder fixing seat, 103-second lifting drive, 104-second fixing seat, 105-lower cylinder lifting plate fixing screw, 106-second baffle ring lifting rod, 107-second adjustment block, 108-second airflow baffle ring, 109-upper cylinder fixing seat, 110-first lifting drive, 111-first fixing seat, 112-first baffle ring lifting rod, 113-chamber lining, 114-first guide sleeve, 115-second guide sleeve, 116-first adjustment block, 117-first airflow baffle ring, 118-127-overlapping baffle ring, 128-first A fixing screw, 129-a first adjusting block screw, 130-a second adjusting block screw, 131-a second fixing screw, 132-an electrode insulating seat, 133-an electrode cover, 134-an electrostatic suction cup, 135-a bias electrode, 136-a shielding cover, 137-a plasma coupling coil, 138-a ceramic dielectric window, 139-a nozzle, 140-an excitation source matching network, 141-an excitation source RF power supply, 142-a gas source, 143-a pressure control valve, 144-a vacuum pump, 145-a bias matching network, 146-a bias RF power supply, 147-a chamber cover, 148-a wafer focusing ring. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The adjustable gas flow etching machine provided in the embodiment of the present invention comprises: a reaction chamber 101, a nozzle 139, a wafer carrier and a gas flow control system, and its structure can refer to Figure 1 It should be noted that the wafer carrier is located in the middle of the reaction chamber 101 and is used to place the wafer;

[0053] The airflow control system includes: a first airflow baffle ring 117, the structure of which can be referred to Figure 1 , Figure 2 and Figure 4 ;

[0054] The first airflow baffle ring 117 is disposed in the reaction chamber 101 and is located between the nozzle 139 and the wafer stage;

[0055] A vent hole is formed at a position of the first airflow baffle ring 117 opposite to the nozzle 139 .

[0056] The working principle and purpose of the above scheme are as follows:

[0057] In the prior art, the gas ejected from the nozzle has uneven density and distribution in the area above the wafer stage, and diffuses disorderly around the area. The gas flow direction can be referred to Figure 5 ;

[0058] The present invention sets a first airflow baffle ring 117, and the gas is ejected from the nozzle 139, passes through the vent holes of the first airflow baffle ring 117, and the vent holes can gather the airflow to the center above the wafer, and then spray it to the wafer on the wafer carrier. In the present invention, the gas passing through the vent holes has uniform density and distribution, and is sprayed from the vent holes to the wafer in an orderly manner. The airflow direction can be referred to Figure 6 ;

[0059] It can be seen from the above that the gas is gathered by providing the first gas flow baffle ring 117, thereby solving the technical problem of poor uniformity of the etcher.

[0060] Specifically, the first airflow baffle ring 117 is a circular ring, the outer diameter of which matches the inner diameter of the side wall of the chamber liner 113 in the reaction chamber 101. Figure 1 , and a gap is left between the outer circle of the first airflow baffle ring 117 and the side wall of the chamber liner 113 to prevent particles from gathering. Through such a design, particles fall under the action of gravity and cannot gather between the first airflow baffle ring 117 and the side wall of the chamber liner 113.

[0061] Preferably, the airflow control system further comprises: a first lifting device;

[0062] The first lifting device can make the first airflow baffle ring 117 move up and down. This design changes the distance between the nozzle 139 and the wafer by adjusting the height L2 of the first airflow baffle ring 117, that is, the distance between the first airflow baffle ring 117 and the bottom surface of the chamber liner 113 (refer to Figure 3 ), thereby controlling the flow direction and flow rate of the gas flow, and further adjusting the uniformity of etching. It should be noted that the chamber liner 113 includes a side wall portion extending in the axial direction, and a bottom surface portion extending in the radial direction.

[0063] In this solution, the first lifting mechanism includes: a first lifting drive 110 and a first transmission mechanism, the structure of which can be referred to Figure 1 and Figure 2 ;

[0064] The first transmission mechanism is located between the wafer stage and the reaction chamber 101, which can fully utilize the space in the chamber without affecting the operation of the original structure. In this embodiment, the wafer stage can specifically include an electrode insulating seat 132, an electrode cover 133, an electrostatic chuck 134, a bias electrode 135 and a wafer focusing ring 148.

[0065] The first lifting drive 110 is disposed outside the reaction chamber 101 . This design can save space in the chamber.

[0066] Furthermore, the first transmission mechanism includes: a first baffle ring lifting rod 112 and a first guide sleeve 114, the structure of which can be referred to Figure 1 and Figure 2 ;

[0067] The first end of the first baffle ring lifting rod 112 is connected to the first airflow baffle ring 117, and the second end of the first baffle ring lifting rod 112 is connected to the first lifting drive 110. In this design, the first lifting drive 110 drives the first airflow baffle ring 117 to perform lifting motion through the first baffle ring lifting rod 112;

[0068] The middle part of the first baffle lifting rod 112 is disposed in the first guide sleeve 114, which is disposed on the bottom surface of the chamber liner 113 disposed in the reaction chamber 101 and is located between the wafer stage and the reaction chamber 101. It should be noted that the first guide sleeve 114 serves a guiding role.

[0069] Specifically, the first transmission mechanism also includes: a first adjustment block 116 and a first fixing seat 111, the structure of which can refer to Figure 1 and Figure 2 ;

[0070] The first end of the first baffle ring lifting rod 112 is connected to the first end face of the first adjustment block 116 through the first adjustment block screw 129, the second end face of the first adjustment block 116 is connected to the first airflow baffle ring 117 through the first fixing screw 128, and the second end of the first baffle ring rod 112 is connected to the first lifting drive 110 through the first fixing seat 111. It should be noted that the first adjustment block 116 plays the role of adjustment support; it should also be noted that the first fixing seat 111 plays the role of fixing support.

[0071] As a preferred embodiment, the airflow control system further comprises: a stacked baffle ring, the specific structure of which can be referred to Figure 2 and Figure 4 The outer circle of the stacked baffle ring can be removably installed on the inner circle of the first airflow baffle ring 117. It should be noted that through this design, different stacked baffle rings can be replaced according to process requirements without removing and replacing the first airflow baffle ring 117, which is convenient and quick; it should also be noted that the inner circle of the first airflow baffle ring 117 is the aforementioned vent hole, which is coaxial with the nozzle 139.

[0072] In this solution, the number of superimposed retaining rings is multiple of the inner and outer sleeves. The specific structure can be referred to Figure 2 and Figure 4The outer circle of the inner stacked baffle ring can be detachably installed on the inner circle of the outer stacked baffle ring, and the outer circle of the outermost stacked baffle ring can be detachably installed on the inner circle of the first airflow baffle ring 117. By designing and arranging multiple baffle rings with different inner diameters in a stacked manner to meet different process requirements, the assembly can be achieved by overlapping the inner and outer circles of the conical structure with the upper part larger and the lower part smaller.

[0073] Further, the inner diameter of the first airflow baffle ring 117 is 120% of the wafer diameter, and the inner diameter of the innermost superimposed baffle ring is 80% of the wafer diameter. It should be noted that the diameter of the first airflow baffle ring 117 (wafer size ± 20%), such as the diameter of an 8-inch wafer is 200 mm, the diameter range of the first airflow baffle ring 117 is 160 to 240 mm.

[0074] Specifically, the airflow control system further includes: a second airflow baffle ring 108, the structure of which can be referred to Figure 1 and Figure 2 ,

[0075] The second airflow baffle ring 108 is disposed between the wafer stage and the reaction chamber 101 and is located below the first airflow baffle ring 117. An annular air passage is formed between the outer circle of the second airflow baffle ring 108 and the reaction chamber 101. It should be noted that the second airflow baffle ring 108 cooperates with the first airflow baffle ring 117 to control the speed of the fluid and thus adjust the uniformity (refer to Figure 7 ); It should also be noted that the outer diameter of the second airflow baffle ring 108 can be set to be smaller than the inner diameter of the reaction chamber 101 to form an annular air passage.

[0076] Preferably, the second airflow baffle ring 108 is a circular ring coaxial with the wafer stage, and its inner diameter matches the outer diameter of the wafer stage. Figure 4 It should be noted that the second airflow baffle ring 108 and the wafer stage have a clearance fit; it should also be noted that such a design can increase the fluid retention area and thus adjust the uniformity (refer to Figure 7 ).

[0077] In this solution, the airflow control system further includes: a second lifting device;

[0078] The second lifting device can make the second airflow baffle ring 108 move up and down. This design changes the distance L3 between the second airflow baffle ring 108 and the first airflow baffle ring 117 by adjusting the height L1 of the second airflow baffle ring 108, that is, the distance between the second airflow baffle ring 108 and the bottom surface of the chamber liner 113 (refer to Figure 3 ), thereby controlling the direction and velocity of the airflow, and further adjusting the uniformity of etching.

[0079] Further, the second lifting device includes: a second lifting drive 103 and a second transmission mechanism, the structure of which can refer to Figure 1 and Figure 2 ;

[0080] The second transmission mechanism is located between the wafer stage and the reaction chamber 101, which can fully utilize the space inside the chamber without affecting the operation of the original structure;

[0081] The second lifting drive 103 is disposed outside the reaction chamber 101 . This design can save space in the chamber.

[0082] Further, the second transmission mechanism includes: a second baffle ring lifting rod 106 and a second guide sleeve 115, the structure of which can be referred to Figure 1 and Figure 2 ;

[0083] The first end of the second baffle ring lifting rod 106 is connected to the second airflow baffle ring 108, and the second end of the second baffle ring lifting rod 106 is connected to the second lifting drive 103. In this design, the second lifting drive 103 drives the second airflow baffle ring 108 to perform lifting motion through the second baffle ring lifting rod 106;

[0084] The middle part of the second retaining ring lifting rod 106 is disposed in the second guide sleeve 115, which is disposed on the bottom surface of the chamber liner 113 disposed in the reaction chamber 101 and is located between the wafer stage and the reaction chamber 101. It should be noted that the second guide sleeve 115 plays a guiding role.

[0085] Specifically, the second transmission mechanism also includes: a second adjustment block 107 and a second fixing seat 104, the structure of which can be referred to Figure 1 and Figure 2 ;

[0086] The first end of the second baffle ring lifting rod 106 is connected to the first end face of the second adjustment block 107 through the second adjustment block screw 130, the second end face of the second adjustment block 107 is connected to the second airflow baffle ring 108 through the second fixing screw 131, and the second end of the second baffle ring lifting rod 106 is connected to the second lifting drive 103 through the second fixing seat 104. It should be noted that the second adjustment block 107 plays the role of adjustment support; it should also be noted that the second fixing seat 104 plays the role of fixing support.

[0087] As an option, the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 is 20-70 mm, and the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 is L3 (reference Figure 2 ), different values ​​of L3 determine different flow rates of the airflow.

[0088] The embodiment of the present invention further provides an etching method, using the above-mentioned etcher with adjustable gas flow, comprising the steps of:

[0089] S1, sequentially forming a SiO2 insulating layer and an Al layer on a semiconductor substrate;

[0090] S2. Set up an airflow control system, including: adjusting the diameter of the vent hole:

[0091] S3. Etching the Al layer.

[0092] Furthermore, the airflow control system is provided, further comprising: adjusting the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108, namely the aforementioned L3 (reference Figure 3 ), thereby controlling the direction and velocity of the airflow, and further adjusting the uniformity of etching.

[0093] Specifically, before setting the airflow control system, the method further includes: obtaining optimal values ​​of the vent hole diameter and height difference, including the steps of:

[0094] The height difference remains unchanged, the etching rate uniformity under different vent hole diameters is obtained, and the vent hole diameter corresponding to the optimal etching rate uniformity is obtained by comparison;

[0095] The diameter of the vent hole remains unchanged, and the uniformity of the etching rate under different height differences is obtained, and the height difference corresponding to the optimal uniformity of the etching rate is compared.

[0096] Preferably, obtaining the optimal values ​​of the vent hole diameter and height difference includes:

[0097] The diameter of the vent hole is set to 220 mm, and the uniformity of the etching rate under the height difference of 20, 30, 40 and 50 mm is obtained. The height difference corresponding to the optimal uniformity of the etching rate is obtained by comparison. In this scheme, the diameter of the vent hole is adjusted to 220 mm, and the values ​​of the height difference L3 between the first airflow baffle ring 117 and the second airflow baffle ring 108 are adjusted to 20, 30, 40 and 50 mm respectively (reference Figure 3 ), under different height differences, the etching rate uniformity was recorded. It was found that when the height difference was 30mm, the uniformity of the 8-inch aluminum wafer could reach 3.1%. Fig. 9 .

[0098] The height difference is set to 30 mm, and the uniformity of the etching rate when the vent diameters are 210, 220 and 230 mm is obtained. The vent diameters corresponding to the optimal uniformity of the etching rate are obtained by comparison. In this scheme, the height difference L3 between the first airflow baffle ring 117 and the second airflow baffle ring 108 is adjusted to 30 mm, and the vent diameters are adjusted to 210, 220 and 230 mm (reference Figure 2 and Figure 3), under different diameters, the etching rate uniformity was recorded, and it was found that when the diameter was 220mm, the uniformity of the 8-inch aluminum wafer could reach 3.1%. Figure 8 .

[0099] The present invention is further described below in conjunction with specific embodiments:

[0100] like Figure 1 and Figure 2 As shown, the main components of the etching chamber of the plasma etcher of the present invention include: a reaction chamber 101, a chamber liner 113, a plasma coupling coil 137, a chamber cover 147, a ceramic dielectric window 138, an excitation source RF power supply 141, an excitation source matching network 140, a shielding cover 136, a gas source 142, a nozzle 139, a bias RF power supply 146, a bias matching network 145, a pressure control valve 143, a vacuum pump 144, an electrode cover 133, a wafer focusing ring 148, a first airflow baffle ring 117, a first guide sleeve 114, a first baffle ring lifting rod 112, and a first lifting drive The cylinder fixing seat 102 includes a first air flow baffle ring 108, a second guide sleeve 115, a second baffle ring lifting rod 106, a second lifting drive 103, a second adjusting block screw 130, an electrode insulating seat 132, a lower cylinder fixing seat 102, a lower cylinder lifting plate fixing screw 105, an upper cylinder fixing seat 109, a bias electrode 135, an electrostatic suction cup 134, a first adjusting block screw 129, a first adjusting block 116, a first fixing screw 128, a second fixing screw 131, a second adjusting block 107, a second fixing seat 104 and a plurality of sets of superimposed baffle rings 118 to 127.

[0101] As described above, in the adjustable airflow combined baffle ring structure of the present invention, the first airflow baffle ring 117 and the second airflow baffle ring 108 can be lifted and lowered respectively under the drive of the first lifting drive 110 and 103. A distance is left between the outer circle of the first airflow baffle ring 117 and the chamber liner 113 to prevent particle aggregation.

[0102] like Figure 2 and Figure 3 As shown, the adjustable airflow combined baffle ring structure described in the present invention, the gas source 142 provides process gas to be sprayed into the reaction chamber 101 through the nozzle 139, and plasma is generated under the action of the plasma coupling coil 137. The bias electrode 135 provides bias to accelerate the plasma to bombard the wafer above the electrostatic chuck 134. The first airflow baffle ring 117 can gather the airflow to the center above the wafer, and can react with the wafer more directly. The second airflow baffle ring 108 is combined with the electrostatic chuck 134 and the electrode cover 133 to increase the gas retention area, making it more difficult for the gas to be directly drawn away, and increasing the reaction time between the gas and the wafer. The first airflow baffle ring 117 and the second airflow baffle ring 108 jointly form a system for controlling airflow.

[0103] like Figure 2 and Figure 3 As shown, the second airflow baffle ring 108 can be raised and lowered, that is, the height L1 value can be changed in the figure, and the first airflow baffle ring 117 can also be raised and lowered, that is, the height L2 value can be changed in the figure. In this way, by adjusting the height values ​​of L1 and L2, different height combinations can be obtained, and the gap between the first airflow baffle ring 117 and the second airflow baffle ring 108 can also obtain different values, that is, L3 values. By adjusting the height L2 of the first airflow baffle ring 117 and the height L1 of the second airflow baffle ring 108 and the height distance L3 between the first airflow baffle ring 117 and the second airflow baffle ring 108 respectively, different airflow directions and airflow speeds can be obtained. The heights of L1 and L2 determine the airflow direction, and the value of L3 determines the airflow speed. In this way, the uniformity of etching is adjusted by adjusting the airflow direction and airflow speed. In different etching processes, it is only necessary to adjust the different value combinations of L1, L2, and L3 by raising and lowering the first airflow baffle ring 117 and the second airflow baffle ring 108 to meet the uniformity adjustment of different processes.

[0104] like Figure 2 , Figure 3 and Figure 4 As shown, in different etching processes, uniformity adjustment also has different requirements for the inner diameter of the first airflow baffle ring 117. We set multiple baffle rings with different inner diameters in a superimposed manner to meet different process requirements. That is, detachable and superimposed baffle rings 118 to 127 are set in the first airflow baffle ring 117, so that different combined inner diameters, i.e., D values, are finally obtained to meet the requirements of different processes. The advantage is that there is no need to disassemble and replace the first airflow baffle ring 117, which is convenient and fast.

[0105] The above-mentioned adjustable airflow combined baffle ring structure:

[0106] The first airflow baffle ring 117 and the second airflow baffle ring 108 can be respectively raised and lowered to different heights and distances from each other to adjust the etching uniformity of different processes. Overlay baffle rings 118 to 127 with different inner diameters can be placed on the first airflow baffle ring 117 to gather the airflow to different degrees to further adjust the etching uniformity of different processes.

[0107] In summary, the adjustable airflow combined baffle ring structure of the present invention can adjust the flow direction and flow rate of the airflow in the etching chamber of the plasma etcher, thereby improving the etching uniformity.

[0108] Figure 3 This is a schematic diagram of the main airflow direction in the chamber. Figure 6 This is a schematic diagram of the flow direction of the fluid after flow control in the present invention. Figure 7 The present invention is a schematic diagram of a method for improving uniformity.

[0109] Key points of the invention: The plasma concentration in the chamber of the etcher is adjusted by an airflow control system; the etcher realizes the lifting and lowering of the airflow baffle ring by setting a lifting device; the etcher adjusts the uniformity of etching by adjusting the airflow direction and airflow velocity.

[0110] Methods:

[0111] In order to solve the problem of etching uniformity of a plasma etcher, the present invention proposes a method for optimizing etching uniformity by using a combined baffle ring structure.

[0112] This patent discloses a method for optimizing etching uniformity using a combined baffle ring structure, the specific steps of which are: first assembling the above-mentioned combined baffle ring structure device in the etching chamber, and then etching the wafer using chlorine-based gas, bromine-based gas, fluorine-based gas or a combination of these gases. It is characterized in that better etching uniformity is achieved by adjusting the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 and the inner diameter of the first airflow baffle ring 117 and the process parameters.

[0113] A device for optimizing etching uniformity using a combined baffle ring, wherein the height difference between the upper and lower ascending and descending airflow baffle rings can be adjusted within a range of 20-70 mm.

[0114] A device for optimizing etching uniformity using a combined baffle ring, wherein the inner diameter of a first airflow baffle ring 117 can be adjusted within a range of 150-240 mm.

[0115] A method for optimizing etching uniformity by using a combined baffle ring, wherein the etching method adopted is a plasma etching method.

[0116] A method for optimizing etching uniformity using a combined retaining ring can be used to improve the uniformity of Al, AlN, AlScN, Mo or W processes.

[0117] A method for optimizing etching uniformity by using a combined baffle ring, wherein the etching gas is a chlorine-based gas, a bromine-based gas, a fluorine-based gas or a combined gas thereof.

[0118] The RF power range of the ICP machine used in the dry etching method is 0-1000W.

[0119] The RF power range of the ICP machine used in the dry etching method is 0-800W.

[0120] The dry etching method uses a chamber pressure of 2-50 mTorr and a total flow rate of 50-250 sccm.

[0121] The dry etching method requires the chiller temperature of the ICP etcher to be 0-50°C.

[0122] Example 1: This example demonstrates the process of optimizing wafer etching uniformity by the etching method;

[0123] Step 1: forming a SiO2 insulating layer and an Al layer in sequence on a semiconductor substrate;

[0124] Step 2: Add a combined baffle ring structure device to the ICP chamber, adjust the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 to 30 mm, and adjust the inner diameter of the first airflow baffle ring 117 to 210, 220 and 230 mm, which can optimize the uniformity of 8-inch aluminum wafers to 3.1%.

[0125] Step 3: Use an ICP etcher to etch the Al layer. During the etching process, the ICP etcher parameters are set as follows: upper RF power 1000W, lower RF power 150W, ICP etcher chiller temperature 35°C, chamber pressure 10mTorr, and the gases used are 30sccmBCl3 and 120sccmCl2. The etching amount is half of the film thickness, and the etching rate uniformity is as follows: Figure 8 As shown, the uniformity of 8-inch aluminum wafer can be optimized to 3.1% (49-point range method).

[0126] Example 2: This example demonstrates the process of optimizing wafer etching uniformity by the etching method;

[0127] Step 1: forming a SiO2 insulating layer and an Al layer in sequence on a semiconductor substrate;

[0128] Step 2: Add a combined baffle ring structure device to the ICP chamber, adjust the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 to 20, 30, 40 and 50 mm, and the inner diameter of the first airflow baffle ring 117 is 220 mm;

[0129] Step 3: Use an ICP etcher to etch the Al layer. During the etching process, the ICP etcher parameters are set as follows: upper RF power 1000W, lower RF power 150W, ICP etcher chiller temperature 35°C, chamber pressure 10mTorr, and the gases used are 30sccmBCl3 and 120sccmCl2. The etching amount is half of the film thickness, and the etching rate uniformity is as follows: Fig. 9 As shown, the uniformity of 8-inch aluminum wafer can be optimized to 3.1% (49-point range method).

[0130] Example 3: This example demonstrates the process of optimizing wafer etching uniformity by the etching method;

[0131] Step 1: forming a SiO2 insulating layer and an Al layer in sequence on a semiconductor substrate;

[0132] Step 2: Install a combined baffle ring structure device on the ICP chamber, adjust the height difference between the first airflow baffle ring 117 and the second airflow baffle ring 108 to 30 mm, and adjust the inner diameter of the first airflow baffle ring 117 to 220, 170, 160 and 150 mm, which can optimize the uniformity of 6-inch aluminum wafers to 3.5%.

[0133] Step 3: Use an ICP etcher to etch the Al layer. During the etching process, the ICP etcher parameters are set as follows: upper RF power 1000W, lower RF power 150W, ICP etcher chiller temperature 35°C, chamber pressure 10mTorr, and the gases used are 30sccmBCl3 and 120sccmCl2. The etching amount is half of the film thickness, and the etching rate uniformity is as follows: Fig.10 As shown, the uniformity of a 6-inch aluminum wafer can be optimized to 3.5% (49-point range method).

[0134] Key points of the invention: The etcher realizes the lifting and lowering of the airflow baffle ring by setting a lifting device; the etcher realizes the uniformity of the aluminum wafer by adjusting the airflow direction and airflow velocity; the etcher etches the Al layer.

[0135] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0136] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An etcher with adjustable gas flow, characterized in that: include: A reaction chamber (101), a nozzle (139), a wafer carrier and an air flow control system; The airflow control system comprises: a first airflow baffle ring (117); The first airflow baffle ring (117) is arranged in the reaction chamber (101) and is located between the nozzle (139) and the wafer carrier; A vent hole is provided at a position of the first airflow baffle ring (117) opposite to the nozzle (139).

2. The etcher with adjustable gas flow according to claim 1, characterized in that: The first airflow baffle ring (117) is a circular ring, the outer diameter of which matches the inner diameter of the side wall of the chamber liner (113) in the reaction chamber (101), and a gap is left between the outer circle of the first airflow baffle ring (117) and the side wall of the chamber liner (113) to prevent particle aggregation.

3. The etcher with adjustable gas flow according to claim 1, characterized in that: The airflow control system further comprises: a first lifting device; The first lifting device can enable the first airflow blocking ring (117) to move up and down.

4. The etcher with adjustable gas flow according to claim 3, characterized in that: The first lifting mechanism comprises: a first lifting drive (110) and a first transmission mechanism; The first transmission mechanism is located between the wafer carrier and the reaction chamber (101); The first lifting drive (110) is arranged outside the reaction chamber (101).

5. The etcher with adjustable gas flow according to claim 4, characterized in that: The first transmission mechanism comprises: a first baffle ring lifting rod (112) and a first guide sleeve (114); The first end of the first baffle ring lifting rod (112) is connected to the first airflow baffle ring (117), and the second end of the first baffle ring lifting rod (112) is connected to the first lifting drive (110); The middle portion of the first retaining ring lifting rod (112) is arranged in the first guide sleeve (114), and the first guide sleeve (114) is arranged on the bottom surface of the chamber liner (113) in the reaction chamber (101) and is located between the wafer carrier and the reaction chamber (101).

6. The etcher with adjustable gas flow according to claim 5, characterized in that: The first transmission mechanism further comprises: a first adjustment block (116) and a first fixing seat (111); The first end of the first baffle ring lifting rod (112) is connected to the first end face of the first adjustment block (116) via a first adjustment block screw (129), the second end face of the first adjustment block (116) is connected to the first airflow baffle ring (117) via a first fixing screw (128), and the second end of the first baffle ring rod (112) is connected to the first lifting drive (110) via the first fixing seat (111).

7. The etcher with adjustable gas flow according to claim 1, characterized in that: The airflow control system further comprises: a stacked baffle ring; the outer circle of the stacked baffle ring can be detachably mounted on the inner circle of the first airflow baffle ring (117).

8. The etcher with adjustable gas flow according to claim 7, characterized in that: The number of the stacked baffle rings is multiple, with inner and outer arrangements. The outer circle of the inner stacked baffle ring can be detachably mounted on the inner circle of the outer stacked baffle ring, and the outer circle of the outermost stacked baffle ring can be detachably mounted on the inner circle of the first airflow baffle ring (117).

9. The etcher with adjustable gas flow according to claim 8, characterized in that: The inner diameter of the first airflow baffle ring (117) is 120% of the diameter of the wafer, and the inner diameter of the innermost stacked baffle ring is 80% of the diameter of the wafer.

10. The etcher with adjustable gas flow according to any one of claims 1 to 9, characterized in that: The airflow control system further comprises: a second airflow baffle ring (108); The second airflow baffle ring (108) is arranged between the wafer carrier and the reaction chamber (101), and is located below the first airflow baffle ring (117), and an annular air passage is formed between the outer circle of the second airflow baffle ring (108) and the reaction chamber (101).

11. The etcher with adjustable gas flow according to claim 10, characterized in that: The second airflow baffle ring (108) is a circular ring coaxial with the wafer carrier, and its inner diameter matches the outer diameter of the wafer carrier.

12. The etcher with adjustable gas flow according to claim 10, characterized in that: The airflow control system further includes: a second lifting device; The second lifting device can enable the second airflow blocking ring (108) to move up and down.

13. The etcher with adjustable gas flow according to claim 12, characterized in that: The second lifting device comprises: a second lifting drive (103) and a second transmission mechanism; The second transmission mechanism is located between the wafer carrier and the reaction chamber (101); The second lifting drive (103) is arranged outside the reaction chamber (101).

14. The etcher with adjustable gas flow according to claim 13, characterized in that: The second transmission mechanism comprises: a second baffle ring lifting rod (106) and a second guide sleeve (115); The first end of the second baffle ring lifting rod (106) is connected to the second airflow baffle ring (108), and the second end of the second baffle ring lifting rod (106) is connected to the second lifting drive (103); The middle part of the second retaining ring lifting rod (106) is arranged in the second guide sleeve (115), and the second guide sleeve (115) is arranged on the bottom surface of the chamber liner (113) in the reaction chamber (101) and is located between the wafer carrier and the reaction chamber (101).

15. The etcher with adjustable gas flow according to claim 14, characterized in that: The second transmission mechanism further comprises: a second adjustment block (107) and a second fixing seat (104); The first end of the second baffle ring lifting rod (106) is connected to the first end face of the second adjustment block (107) via a second adjustment block screw (130), the second end face of the second adjustment block (107) is connected to the second airflow baffle ring (108) via a second fixing screw (131), and the second end of the second baffle ring lifting rod (106) is connected to the second lifting drive (103) via the second fixing seat (104).

16. The etcher with adjustable gas flow according to claim 10, characterized in that: The height difference between the first airflow baffle ring (117) and the second airflow baffle ring (108) is 20-70 mm.

17. An etching method, characterized in that: An etcher using the adjustable gas flow as claimed in claims 1 to 16, comprising the steps of: S1, sequentially forming a SiO2 insulating layer and an Al layer on a semiconductor substrate; S2, setting the airflow control system, including: adjusting the diameter of the vent hole; S3, etching the Al layer.

18. The etching method according to claim 17, characterized in that: The setting of the airflow control system further includes: adjusting the height difference between the first airflow baffle ring (117) and the second airflow baffle ring (108).

19. The etching method according to claim 18, characterized in that: Before setting the airflow control system, the method further includes: obtaining the optimal values ​​of the vent hole diameter and the height difference, including the steps of: The height difference remains unchanged, the etching rate uniformity under different vent hole diameters is obtained, and the vent hole diameter corresponding to the optimal etching rate uniformity is obtained by comparison; The diameter of the vent hole remains unchanged, and the uniformity of the etching rate under different height differences is obtained, and the height difference corresponding to the optimal uniformity of the etching rate is obtained by comparison.

20. The etching method according to claim 19, characterized in that: The obtaining of the optimal values ​​of the vent hole diameter and the height difference comprises: The diameter of the vent hole is set to 220 mm, and the uniformity of the etching rate when the height difference is 20, 30, 40 and 50 mm is obtained, and the height difference corresponding to the optimal uniformity of the etching rate is obtained by comparison; The height difference is set to 30 mm, and the etching rate uniformity is obtained when the vent hole diameters are 210, 220 and 230 mm respectively, and the vent hole diameters corresponding to the optimal etching rate uniformity are obtained by comparison.

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