阅读说明：本技术 一种晶圆抛光装置 (Wafer polishing device ) 是由 邓耀敏 杨渊思 于 2021-10-20 设计创作，主要内容包括：本发明公开了一种晶圆抛光装置,包括第二压力介质腔体,用于感应压力变化；多孔盘,带有多个通孔,下表面包覆柔性单腔膜；导通阀单元,用于第二压力介质腔体和第三压力介质腔体之间的导通或隔离,其至少包括导通阀座,导通阀,及弹性件,导通阀座下端伸入通孔内,导通阀的下端突出于导通阀座的下端面；导通阀座与多孔盘由柔性单腔膜覆盖配合形成第三压力介质腔体；第一压力介质腔体；于第三压力介质腔体形成负压,使得多孔盘和柔性单腔膜上吸附有晶圆时,导通阀克服弹性件的力相对导通阀座发生移动,将第二压力介质腔体和第三压力介质腔体相连通。本发明实现了柔性单腔膜正导通机制,可准确、快速判断晶圆的装载状态,碎片风险小。(The invention discloses a wafer polishing device, which comprises a second pressure medium cavity, a first pressure medium cavity and a second pressure medium cavity, wherein the second pressure medium cavity is used for sensing pressure change; the porous disc is provided with a plurality of through holes, and the lower surface of the porous disc is coated with the flexible single-cavity film; the conducting valve unit is used for conducting or isolating the second pressure medium cavity and the third pressure medium cavity and at least comprises a conducting valve seat, a conducting valve and an elastic piece, the lower end of the conducting valve seat extends into the through hole, and the lower end of the conducting valve protrudes out of the lower end face of the conducting valve seat; the conducting valve seat and the porous disc are covered and matched by the flexible single-cavity film to form a third pressure medium cavity; a first pressure medium chamber; and negative pressure is formed in the third pressure medium cavity, so that when the wafer is adsorbed on the porous disc and the flexible single-cavity film, the conduction valve overcomes the force of the elastic piece and moves relative to the conduction valve seat, and the second pressure medium cavity is communicated with the third pressure medium cavity. The invention realizes a positive conduction mechanism of the flexible single-cavity film, can accurately and quickly judge the loading state of the wafer and has small risk of fragments.)

1. A wafer polishing apparatus, comprising:

a second pressure medium chamber (2) for sensing pressure changes;

a porous plate (5) having a plurality of through holes (51), the lower surface of which is coated with a flexible single-cavity membrane (6) for supporting a wafer (7);

the conducting valve unit (4) is arranged between the second pressure medium cavity (2) and the third pressure medium cavity (3) and used for conducting or isolating the second pressure medium cavity (2) and the third pressure medium cavity (3), and at least comprises a conducting valve seat (41), a conducting valve (42) capable of moving relative to the conducting valve seat (41), and an elastic piece (43) abutted against the conducting valve (42), wherein the lower end of the conducting valve seat (41) extends into the through hole (51), and the lower end of the conducting valve (42) protrudes out of the lower end face of the conducting valve seat (41);

the conducting valve seat (41) and the porous disc (5) are covered and matched by a flexible single-cavity film (6) to form a third pressure medium cavity (3);

the first pressure medium cavity (1) is used for controlling the porous disc (5), the second pressure medium cavity (2) and the third pressure medium cavity (3) to move up and down;

and negative pressure is formed in the third pressure medium cavity (3), so that when the wafer (7) is adsorbed on the porous disc (5) and the flexible single-cavity film (6), the conducting valve (42) overcomes the force of the elastic piece (43) to move relative to the conducting valve seat (41), and the second pressure medium cavity (2) is communicated with the third pressure medium cavity (3).

2. The wafer polishing apparatus as set forth in claim 1, wherein: when the third pressure medium cavity (3) is in a negative pressure state, the lower end face of the conducting valve seat (41) is flush with the lower surface of the porous disc (5).

3. The wafer polishing apparatus as set forth in claim 1, wherein: the inner diameter of the through hole (51) is larger than the outer diameter of the conducting valve seat (41), so that a gap (511) for deformation of the flexible single-cavity membrane (6) is formed between the outer wall of the conducting valve seat (41) and the inner wall of the through hole (51).

4. The wafer polishing apparatus as set forth in claim 3, wherein: the radial width of the gap (511) is S, the thickness of the flexible single-cavity film (6) is H, and S is larger than or equal to 2H.

5. The wafer polishing apparatus as set forth in claim 4, wherein: the length of the conducting valve (42) protruding out of the lower end face of the conducting valve seat (41) is D, and D is larger than or equal to 1/10H.

6. The wafer polishing apparatus as set forth in claim 5, wherein: the outer diameter of the lower end face of the conducting valve seat (41) is d1, the outer diameter of the conducting valve (42) is d2, and d1 is not less than d2+ H.

7. The wafer polishing apparatus as set forth in claim 1, wherein: the center of the conducting valve seat (41) coincides with the center of the through hole (51) where the conducting valve seat is located.

8. The wafer polishing apparatus as set forth in claim 1, wherein: the through holes (51) are all round, oval, quadrilateral, special-shaped or the combination of at least two shapes.

Technical Field

The invention belongs to the technical field of semiconductor integrated circuit chip manufacturing, and particularly relates to a wafer polishing device.

Background

In the process of the CMP equipment, a polishing head is arranged at a wafer loading bracket, is loaded by a wafer loading system and is then transmitted to a polishing pad, detection is needed before the planarization process, the wafer is ensured to be tightly adsorbed on the polishing head, and after the polishing of the polishing table is finished, the polishing head re-adsorbs the wafer from the polishing pad and transfers the wafer to the next polishing pad for further planarization or transfers the wafer to the wafer loading bracket for unloading. Therefore, the polishing head must have the capability of loading the wafer and have a mechanism for detecting the wafer.

In the process of loading the wafer, the medium cavity in the polishing head is pressurized, so that the flexible film connected with the medium cavity expands and is contacted with the wafer to gradually remove air and liquid between the wafer and the flexible film, after the wafer and the flexible film are tightly contacted, negative pressure is applied to the medium cavity, and the wafer adsorbed on the flexible film is ideally loaded onto the polishing head under the action of negative force in the atmospheric direction.

Considering the problem of use cost, polishing heads with single-cavity medium cavities matched with flexible single-cavity films are mostly adopted in the market. The using mechanism of the single-cavity medium cavity and the flexible single-cavity film is a negative conduction mechanism, namely negative pressure is applied to the single-cavity medium cavity, and when the wafer is ideally loaded on the flexible film, the PIN with the larger cross section area can unload part of force transmitted to the guide rod, so that the conduction valve cannot be conducted; when no wafer is on the flexible film or the wafer and the flexible film are not loaded ideally, the flexible film in the hole is extruded by atmospheric pressure to be in hard contact with the PIN, and the atmospheric pressure is transmitted to the guide rod so as to conduct the conduction valve. In other words, the mechanism that the dielectric chamber is ideally loaded with the wafer at the negative pressure is not conducted, and the mechanism that the dielectric chamber is conducted when no wafer or wafer is loaded in a non-ideal manner is called as a negative conduction mechanism.

The negative conduction mechanism has two disadvantages compared to the positive conduction mechanism: 1) the time delay is that the wafer in the negative conduction mechanism can be logically judged only when the pressure feedback value of the detection cavity in a closed state is kept stable after the loading action is finished, and the wafer in the positive conduction mechanism can be conducted with the medium cavity in a very short time when the wafer is loaded, so that the logical judgment can be carried out in advance; 2) the misjudgment risk is that in the positive conduction mechanism, the acting area ratio (acting area/wafer area ratio) of a multi-cavity flexible film in contact with a wafer is large, PIN is small, negative pressure required by conduction of the conduction valve is small, force acting on the wafer in the negative conduction mechanism mainly passes through a plurality of holes, the acting area ratio is small, PIN is large, negative pressure required by relatively fast conduction (no wafer/non-ideal loading judgment) of the conduction valve in a non-wafer/non-ideal loading state is large, high negative pressure can cause overlarge pressure acting on the holes in ideal loading, the conduction valve is further conducted, and the misjudgment risk exists. On the other hand, factors such as the elastic modulus of the flexible film is reduced along with the service life can cause the conduction valve to be conducted by mistake; 3) the piece risk is high, and during the burden switches on, the atmospheric pressure value of using wafer surface during too high negative pressure condition is too big, has the piece risk.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the wafer polishing device which has the advantages of high accuracy and high judgment speed for judging whether the wafer is adsorbed or not and no risk of fragments.

The technical scheme adopted by the invention for solving the technical problems is as follows: a wafer polishing apparatus comprising:

the second pressure medium cavity is used for sensing pressure change;

the porous disc is provided with a plurality of through holes, and the lower surface of the porous disc is coated with a flexible single-cavity film for supporting the wafer;

the conduction valve unit is arranged between the second pressure medium cavity and the third pressure medium cavity, is used for conducting or isolating the second pressure medium cavity and the third pressure medium cavity, at least comprises a conduction valve seat, a conduction valve capable of moving relative to the conduction valve seat and an elastic piece abutted against the conduction valve, the lower end of the conduction valve seat extends into the through hole, and the lower end of the conduction valve protrudes out of the lower end face of the conduction valve seat;

the conducting valve seat and the porous disc are covered and matched by the flexible single-cavity film to form a third pressure medium cavity;

the first pressure medium cavity is used for controlling the porous disc, the second pressure medium cavity and the third pressure medium cavity to move up and down;

and negative pressure is formed in the third pressure medium cavity, so that when the wafer is adsorbed on the porous disc and the flexible single-cavity film, the conduction valve overcomes the force of the elastic piece and moves relative to the conduction valve seat, and the second pressure medium cavity is communicated with the third pressure medium cavity.

According to the invention, through the matching of the conduction valve and the conduction valve seat, when the porous disc and the flexible single-cavity film tightly adsorb a wafer, the adsorption force borne by the wafer is transmitted to the elastic piece through the flexible single-cavity film and the conduction valve, so that the conduction of the conduction valve unit is realized, namely the second pressure medium cavity and the third pressure medium cavity are mutually conducted, the traditional negative conduction mechanism of the flexible single-cavity film is changed, the judgment on whether the polishing device correctly loads the wafer is quicker and more accurate, the wafer adsorption judgment accuracy, timeliness and safety are improved, a multi-gas-path system is not required to be matched, and the use cost is reduced.

Further, when the third pressure medium cavity is in a negative pressure state, the lower end face of the conducting valve seat is flush with the lower surface of the porous plate.

The lower end face of the conducting valve seat is flush with the lower surface of the porous plate, so that the uniform stress distribution of the wafer support is facilitated; when the lower end face of the conduction valve seat is higher than the lower surface of the porous plate too much without a conduction valve seat structure, the flexible single-cavity membrane can form excessive deformation when the negative pressure of the third pressure medium cavity is applied to the through hole area, and when the deformation quantity is large under the influence of the negative pressure, the upward negative pressure is easily larger than the force required by the conduction of the elastic piece, so that the second pressure medium cavity is conducted with the third pressure medium cavity.

Furthermore, the inner diameter of the through hole is larger than the outer diameter of the conducting valve seat, so that a gap for the flexible single-cavity film to deform is formed between the outer wall of the conducting valve seat and the inner wall of the through hole, the negative pressure interval is increased, and the adsorption force applied to the wafer is increased.

The clearance is arranged so that in the process of negative pressure adsorption of the wafer, the flexible single-cavity film forms a negative pressure interval similar to a circular ring shape between the conducting valve seat and the through hole, so that the interval forms adsorption force on the wafer, and further the whole adsorption force on the wafer is increased.

Further, the radial width of the gap is S, the thickness of the flexible single-cavity film is H, and S is larger than or equal to 2H. When the radial width S of the gap is larger than or equal to 2H, the flexible single-cavity film is bent and deformed upwards towards the gap under the negative pressure action of the third pressure medium cavity, and a negative pressure area is formed between the flexible single-cavity film and the wafer, so that the wafer is adsorbed. On the contrary, if the radial width S of the gap is less than 2H, the flexible single-cavity film cannot deform to reduce the adsorption force on the wafer, thereby easily causing the failure of loading the wafer by the polishing apparatus.

Furthermore, the length of the conducting valve protruding out of the lower end face of the conducting valve seat is D, and D is not less than 1/10H. The length D is sufficient to take into account the thickness of the flexible single-cavity membrane and its compressibility. In the process of adsorbing the wafer by the negative pressure of the third pressure medium cavity, the wafer moves upwards under the negative pressure, and the negative pressure is transmitted to the conduction valve from the wafer through the flexible single-cavity film, so that the flexible single-cavity film can generate local compression deformation under the pressure stress of the conduction valve. If the length D is less than the compressive deformation of the flexible single-cavity membrane, the wafer cannot realize the movement of the conduction valve. 1/10H is the minimum amount of compressive deformation of the flexible single-cavity membrane.

Furthermore, the outer diameter of the lower end face of the conducting valve seat is d1, the outer diameter of the conducting valve is d2, and d1 is not less than d2+ H. When the third pressure medium cavity is in a wafer-free state, the negative pressure shrinks the flexible single-cavity film to deform upwards, the flexible single-cavity film finally contacts and covers the end part of the conduction valve and the lower end face of the conduction valve seat, the lower end face of the conduction valve seat faces the flexible single-cavity film to form a support, the conduction valve is only subjected to the negative pressure of the flexible single-cavity film at the local part of the end part and is far smaller than the pre-tightening force of the elastic piece on the conduction valve, and therefore the fact that the flexible single-cavity film cannot conduct the third pressure medium cavity and the second pressure medium cavity when the wafer is not in the wafer-free state is achieved, and therefore the fact that the polishing device does not successfully adsorb the wafer at the moment can be judged. Wherein the critical dimension relation is d1 is more than or equal to d2+ H, and the flexible single-cavity membrane can be supported by the conducting valve seat.

Parameters such as related parameters S, D, d1 and d2 of the conduction valve can be comprehensively adjusted through theoretical calculation, so that the vacuum condition for successfully adsorbing the wafer is reduced in design, and the risk of wafer fragments is greatly reduced.

Further, the center of the conducting valve seat coincides with the center of the through hole where the conducting valve seat is located.

Furthermore, the through holes are all round, or all oval, or all quadrilateral, or all special-shaped, or the combination of at least two of the shapes.

The invention has the advantages that 1) the traditional flexible single-cavity film negative conduction mechanism is changed, the loading state of the wafer can be accurately and quickly judged, and the wafer loading efficiency is improved; 2) the loading pressure is reduced, and the risk of wafer fragments can be reduced; 3) and a multi-gas-path system is not needed to be matched, so that the use cost is reduced.

Drawings

FIG. 1 is a cut-away perspective view of the present invention.

Fig. 2 is a bottom view of the porous plate of the present invention.

FIG. 3 is a cross-sectional view of a wafer not being adsorbed according to the present invention.

Fig. 4 is a cross-sectional view of the flexible single-chamber membrane of the present invention beginning to deform.

FIG. 5 is a cross-sectional view of a wafer being sucked under negative pressure.

FIG. 6 is a cross-sectional view of the wafer under negative pressure but not adsorbed in accordance with the present invention.

Fig. 7 is a pressure feedback graph of the second pressure medium chamber and the third pressure medium chamber when the wafer is tightly adsorbed according to the present invention.

Fig. 8 is a pressure feedback graph of the second pressure medium chamber and the third pressure medium chamber when the wafer is not adsorbed according to the present invention.

FIG. 9 is a sectional view showing a state where the polishing apparatus does not adsorb the wafer in the comparative example.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 3, a wafer polishing apparatus includes a first pressure medium chamber 1, a second pressure medium chamber 2, a third pressure medium chamber 3, a porous plate 5, a flexible single-chamber film 6, and a conduction valve unit 4.

The second pressure medium cavity 2, also called as a detection cavity, is used for sensing pressure change, and judging whether the wafer 7 is loaded successfully or not according to the pressure change in the second pressure medium cavity 2;

a porous plate 5 made of a rigid material and having a plurality of through holes 51, the lower surface of which is coated with a flexible single-chamber membrane 6; the lower surface of the porous disc 5 is a plane, when the wafer 7 is adsorbed by the flexible single-cavity film 6, the porous disc 5 can be used as a main supporting component of the wafer 7, wherein the flexible single-cavity film 6 deforms on the through hole 51 to form a negative pressure space with the wafer 7, and pressure adsorbed on the porous disc 5 is provided for the wafer 7;

the conduction valve unit 4 is arranged between the second pressure medium cavity 2 and the third pressure medium cavity 3 and is used for conducting or isolating the second pressure medium cavity 2 and the third pressure medium cavity 3; the conducting valve unit 4 at least comprises a conducting valve seat 41, a conducting valve 42 capable of moving relative to the conducting valve seat 41, and an elastic piece 43 abutted against the conducting valve 42, wherein the lower end of the conducting valve seat 41 extends into the through hole 51, and the lower end of the conducting valve 42 protrudes out of the lower end surface of the conducting valve seat 41;

specifically, the length of the conducting valve 42 protruding out of the lower end face of the conducting valve seat 41 is defined as D, the thickness of the flexible single-cavity membrane 6 is defined as H, and D is not less than 1/10H;

more specifically, in the present embodiment, the conducting valve seat 41 is substantially cylindrical, the center thereof is provided with a through hole, the through hole 51 is circular, and the center of the conducting valve seat 41 coincides with the center of the through hole 51, that is, the two are concentrically and coaxially arranged; the outer diameter of the lower end face of the conducting valve seat 41 is defined as d1, the outer diameter of the conducting valve 42 is defined as d2, and d1 is not less than d2+ H;

of course, in other embodiments, the conducting valve seat 41 may have another structure, and is not limited to a cylindrical shape; the through hole 51 can also be oval, or quadrangular, or in other special-shaped structures, or a porous plate 5 with through holes of various shapes; the conducting valve seat 41 and the through hole 51 can also be arranged concentrically and coaxially;

the conducting valve seat 41 and the porous disc 5 are covered by the flexible single-cavity film 6 and are matched to form the third pressure medium cavity 3;

the first pressure medium cavity 1 is used for controlling the porous disc 5, the second pressure medium cavity 2 and the third pressure medium cavity 3 to move up and down;

when a negative pressure is formed in the third pressure medium chamber 3, and the wafer 7 is adsorbed on the porous plate 5, the conduction valve 42 moves relative to the conduction valve seat 41 against the force of the elastic member 43, and the second pressure medium chamber 2 and the third pressure medium chamber 3 are communicated with each other.

When the porous disc 5 does not adsorb or closely adsorb the wafer 7, the flexible single-cavity film 6 is wrapped on the end surface of the conduction valve 42, and the force is not enough to overcome the force of the elastic member 43, as shown in fig. 6, so that the conduction valve 42 does not move relative to the conduction valve seat 41, and the second pressure medium cavity 2 and the third pressure medium cavity 3 cannot be conducted and are in an isolated state. In other words, the wafer polishing apparatus of the present invention determines whether the wafer 7 is well adsorbed by using the positive conduction mechanism.

In order to ensure that the wafer 7 is stressed more uniformly when being tightly adsorbed, when the third pressure medium chamber 3 is in a negative pressure state, the lower end surface of the conducting valve seat 41 is flush with the lower surface of the porous plate 5.

In order to avoid that the adsorption force of the position of the conducting valve seat 41 on the wafer 7 is smaller, the inner diameter of the through hole 51 is larger than the outer diameter of the conducting valve seat 41, so that a gap 511 for the flexible single-cavity membrane 6 to deform is formed between the outer wall of the conducting valve seat 41 and the inner wall of the through hole 51.

Specifically, the radial width of the gap 511 is S, the thickness of the flexible single-cavity film 6 is H, and S is greater than or equal to 2H, as shown in FIG. 3.

When a wafer 7 needs to be clamped on a loading support or a polishing pad, the first pressure medium cavity 1 is pressurized in the vertical direction and drives the second pressure medium cavity 2 and the third pressure medium cavity 3 to move downwards, and the polishing device is positioned right above the wafer 7 on the loading support or the polishing pad, as shown in fig. 3;

the second pressure medium cavity 2 and the third pressure medium cavity 3 are pressurized, the flexible single-cavity film 6 generates arc deformation, the flexible single-cavity film 6 and the wafer 7 gradually contact outwards from the center of the wafer 7, air and liquid between the flexible single-cavity film and the wafer 7 can be removed, and tight fit is formed, as shown in fig. 4;

keeping the pressure maintaining state of the second pressure medium cavity 2, applying negative pressure to the third pressure medium cavity 3 tightly adsorbing the wafer 7, making the flexible single-cavity membrane 6 and the wafer 7 move upwards under the action of negative atmospheric force, and after reaching the porous disc 5, the whole body continues to be pressed at the through hole 51 of the porous disc 5, because of the existence of the wafer 7, the negative pressure space of the flexible single-cavity membrane 6 is relatively large, on the other hand, the atmospheric pressure in each direction is transmitted to the flexible single-cavity membrane 6 through the wafer 7 and transmitted to the elastic member 43 through the conduction valve 42, when the upward stroke of the movable member reaches a certain threshold, the conduction valve 42 moves upwards, the conduction valve 42 is conducted, and the second pressure medium cavity 2 and the third pressure medium cavity 3 are conducted to a negative pressure state, as shown in fig. 5.

When the wafer 7 is adsorbed on the flexible single-cavity film 6, the main bodies of the wafer 7, the flexible single-cavity film 6 and the porous disc 5 are in a superposed parallel state, the lower surface of the valve seat 41, the wafer 7 and the flexible single-cavity film 6 are partially in a superposed parallel state, and the wafer 7 is evenly stressed and is not easy to damage.

After the conduction, the continuous negative force will support the wafer 7 upwards to achieve the effect of tightly adsorbing the wafer 7, and the pressure feedback curves of the second pressure medium chamber 2 and the third pressure medium chamber 3 are respectively shown as P2 and P3 in fig. 7.

When the wafer 7 is not loaded ideally on the polishing apparatus, the second pressure medium chamber 2 and the third pressure medium chamber 3 cannot be conducted. Under the condition of non-conduction, the negative pressure of the third pressure medium cavity 3 can press the second pressure medium cavity 2, so that the pressure feedback value of the second pressure medium cavity 2 is increased and finally kept stable. The pressure feedback curves of the second pressure medium cavity 2 and the third pressure medium cavity 3 under the condition of no wafer or non-ideal loading are shown as a schematic diagram 8.

Comparative examples

As shown in fig. 9, the present embodiment is different from the first embodiment in that a communication valve seat structure 41 is absent.

When the polishing apparatus is not loaded with the wafer 7, as shown in fig. 9, the flexible single-cavity membrane 6 contracts into the through hole 51 of the porous plate 5 under the negative pressure, since there is no wafer 7, the flexible single-cavity membrane 6 substantially fits the through hole 51 of the porous plate 5, since there is no large area support effect of the lower surface of the conducting valve seat 41 on the flexible single-cavity membrane 6, due to the flexible nature of the flexible single-cavity membrane 6, only the outer wall of the lower end of the conducting valve 42 is attached, and the force generated to be transmitted upward to the elastic member 43 is not enough to conduct the conducting valve 42.

The foregoing detailed description is intended to illustrate and not limit the invention, which is intended to be within the spirit and scope of the appended claims, and any changes and modifications that fall within the true spirit and scope of the invention are intended to be covered by the following claims.