JP2018117165A - Accommodating means for retaining wafers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved accommodating means in order to achieve more accurate positioning.SOLUTION: The invention relates to accommodating means for accommodating and retaining wafers, including: a retaining surface (1o); retaining means for retaining the wafer on the retaining surface (1o); and compensating means (3, 4, 5, and 6) for at least partially and actively, in particular locally in a controllable manner compensating local and/or global distortions of the wafer. The invention further relates to a method for aligning a first wafer with a second wafer using the accommodating means.SELECTED DRAWING: Figure 3b

Description

  The present invention relates to an apparatus and method for aligning a first wafer with a second wafer as described in the claims.

  These receiving means, sample holders, or chucks are available in a variety of formats, where a flat receiving surface or mounting surface is very important to the receiving means and the increasingly smaller wafers On the surface, it is possible to accurately align and connect over the entire surface of the wafer. This is particularly important when a so-called preliminary connection, in which a wafer is joined to another wafer by means of separable interconnections, is made before the actual connection process. High wafer-to-wafer alignment accuracy is especially necessary for all structures placed on one or both wafers, especially when alignment accuracy or misalignment of less than 2 μm must be achieved. . In the vicinity of the alignment marks, this is particularly successful in the preferred receiving means and alignment devices, so-called aligners, in particular bond aligners. By increasing the distance from the alignment mark, a controlled, complete position with an alignment accuracy or in particular a twist value of less than 2 μm, in particular less than 1 μm, more preferably less than 0.25 μm Matching cannot be achieved.

European Patent Application No. 09012023 European Patent Application No. 10015569

  The object of the present invention is to improve the general receiving means so that more precise alignment can be achieved.

  This object is achieved by the features of the claims.

  Advantageous developments of the invention are given in the dependent claims. In addition, all combinations of at least two of the features given in the specification, the claims, and / or the drawings are included in the scope of the configuration of the present invention. Also, within a given numerical range, the displayed limit value is disclosed as a boundary value and claimed in all combinations.

The present invention is based on the applicant's research results according to Patent Document 1 and Patent Document 2, and in Patent Document 1, it is possible to detect the position of the structure as a position map of the wafer on the entire surface, particularly the surface of each wafer. It is said that. Japanese Patent Application Laid-Open No. H10-260260 determines a local alignment error caused by distortion and / or twist of the first wafer with respect to the second wafer when the first wafer is bonded to the second wafer. ,
A first strain map of strain values along the first contact surface of the first wafer, and / or a second strain map of strain values along the second contact surface of the second wafer, and local The present invention relates to an apparatus having an evaluation means for evaluating a first and / or a second distortion map, which can determine a typical registration error.

  The basic idea of the present invention is to provide a receiving means consisting of several independent active control elements, by means of which the mounting surface of the receiving means, especially in shape and / or temperature, is provided. Can be affected. Here, the active control element is compensated for by a corresponding drive so that local alignment errors or local twists known from the position map and / or the distortion map are compensated, or to a large extent. Used to decrease. Here, not only is the local deviation eliminated, but also the macroscopic deviation or elongation of the wafer in the outer dimensions resulting from the local deviation is simultaneously minimized or corrected.

  Accordingly, as described in the present invention, in particular, the above-described invention relating to position maps, strain maps, and / or stress maps and the alignment disclosed in the above-described invention during wafer contact and bonding. In an in-situ correction combination of the above disadvantages, it is possible to achieve even better alignment by active, particularly local effects on wafer twist.

  According to one advantageous embodiment of the invention, the compensation means can locally influence the temperature of the mounting surface. The local temperature rise on the mounting surface results in local expansion of the wafer held on the mounting surface at this location. The greater the temperature gradient, the greater the expansion of the wafer at this location. Acting on local wafer twisting based on position map and / or distortion map data, in particular a vector estimate of alignment error for each position map and / or distortion map position, or local It is possible to correct the twist of the wafer in a controlled manner.

  In this regard, the vector evaluation is defined as a vector field with a torsion vector, which has been determined by means of one of the two variants of the invention, specifically described below.

  The first version relates to applications where only one of the two wafers is structured. In this case, as required by the present invention, structural deviations, in particular geometric deviations from the desired shape, are detected. In this case, in particular, the deviation of the shape of the exposure field of the step-and-repeat exposure apparatus from the nominally expected shape, which is usually rectangular, is particularly targeted. These deviations, in particular the vector field describing these deviations, can be made based on the detection of the position map of the individual alignment marks, and the individual alignment marks correspond to the exposure field according to Patent Document 1. Alternatively, the vector field can be determined based on a stress map and / or a strain map, and the stress map and / or strain map is obtained by means of Patent Document 2. However, advantageously, this vector field can also be determined and read by any other suitable measurement means, as required in this application. In particular, step-and-repeat lithography systems that are activated for acquisition of these data by means of special test masks and / or test methods are suitable for this measurement.

  The second version relates to applications where two wafers are structured. In this case, as required by the present invention, the vector field of misalignment is calculated for all positions in the position map, particularly the first and second position maps according to the cited document 1. The This vector field is determined in particular for the position of the alignment considered to be ideal according to the technical and / or economic criteria by the material in cited document 2.

  In another advantageous embodiment of the invention, the distortion of the mounting surface can be influenced locally by compensation means, in particular by the arrangement of piezo elements that can be actuated individually, preferably on the back side of the mounting surface. it can. By stretching or contracting, i.e. compressing, the mounting surface, the wafer also deforms correspondingly, in particular by the mounting force acting from the mounting surface of the wafer, in particular stretched or contracted, and thus The wafer can be influenced in a controlled manner by corresponding control means based on the value of the strain map determined for this wafer. One further possibility of giving a twist in the opposite direction to the mounting surface of the wafer to the extent that the shape of the mounting surface can be locally influenced by the compensation means, particularly preferably by mechanical action in the Z direction. Sex occurs. Here, the control of the compensation means is also performed by a control means for performing local control correspondingly dedicated to the compensation means based on the values of the position map and / or the distortion map.

  The control means includes in particular software for performing / calculating the corresponding routine.

  According to another advantageous embodiment of the invention, the mounting surface can be locally exposed to pressure from the back of the mounting surface, in particular hydraulically and / or pneumatically, by means of compensation. In this way, the shape of the mounting surface can be affected as well, and thus the aforementioned effects can be produced. Control is similarly performed by the control means described above.

  Advantageously, the compensation means are provided as a plurality of active control elements in the receiving means, in particular integrated or preferably embedded in the mounting surface. Accordingly, the receiving part of the receiving means can be of a monolithic structure as in the known receiving means.

  Here, it is particularly advantageous if each control element or group of control elements of a plurality of control elements can be operated separately. Thus, the local drive is small extract, especially less than half of the wafer, preferably less than 1/4 of the wafer, preferably less than 1/8 of the wafer, more preferably less than 1/16 of the wafer. It means that a small section can be driven locally by compensation means. It is particularly advantageous if the compensation means can be acted on by at least one control element in each region of the wafer occupied by its own structure.

  The device for which rights are claimed in the present application advantageously comprises the above-mentioned control means in a central control unit which participates in all control processes. However, as claimed in this application, it is conceivable to provide the control means in the receiving means, in particular as a module comprising the entire device.

  The method claimed in this application can be further improved in particular by the repeated acquisition of the position and / or distortion map of the first and / or second wafer after alignment. In this way, it is possible to check whether the alignment is successful after the alignment is completed, as is required in this application. Thus, it is possible to remove wafer pairs with very large alignment errors and re-align them, for example as required by the present application, or to dispose of these wafer pairs. It is done.

  It will be considered that the inventions disclosed in the cited document 1 and / or the cited document 2 are simultaneously disclosed as embodiments for the present invention.

  Other advantages, features, and details of the invention will become apparent from the following description of the preferred embodiment and use of the drawings.

It is a top view of the receiving means in which the right is requested | required in invention of 1st Embodiment. 1b is a cross-sectional view of the receiving means according to section line AA of FIG. It is a top view of the receiving means in which the right is requested | required in invention of 2nd Embodiment. 2b is a cross-sectional view of the receiving means according to section line BB in FIG. 2a. It is a top view of the receiving means in which the right is requested | required in invention of 3rd Embodiment. 3b is a cross-sectional view of the receiving means according to section line CC in FIG. 3a. It is a top view of the receiving means in which the right is requested | required in invention of 4th Embodiment. 4b is a cross-sectional view of the receiving means according to section line DD in FIG. 4a.

  Identical parts / features and parts / features having the same action are identified by the same reference numerals in the figures.

  All four embodiments show a monolithic receiver 1, which is shown as a flat, preferably circular, ring-shaped plate and has a flat mounting surface for receiving and mounting a wafer. 1o. This receiver has a ring-shaped shoulder 1a at the outer peripheral edge.

  The mounting surface 1o forms a receiving plane for receiving the wafer, and this plane extends in the X and Y directions. The Z direction extends perpendicular to the X and Y directions, and the mounting force acting on the wafer is directed in this direction. Wafers are mounted through the openings 2, and a plurality of these openings 2 are uniformly distributed over the mounting surface 1 o, and the wafer is held on the mounting surface 1 o by applying a negative pressure to the opening 2. be able to. As the number of the openings 2 is increased and the diameter of the openings 2 is reduced, the negative pressure used in the openings 2 for mounting the wafer is less likely to cause twisting of the wafer above the openings 2. Become.

  The negative pressure in the opening 2 is applied through a vacuum means (not shown), and this vacuum means applies a negative pressure to the internal space 1i disposed on the back side of the mounting surface 1o. The inner space 1 i is further bounded by an outer peripheral wall 1 w of the receiver 1 and is sealed against the periphery. The opening 2 extends from the mounting surface 1o to the internal space 1i and is thus uniformly exposed to the negative pressure spreading in the internal space 1i.

  The internal space 1 i is further partitioned by a back surface 1 r disposed opposite the mounting surface 1 o and a bottom surface (not shown) of the internal space 1 i, and the back surface 1 r is penetrated by the opening 2.

  In the rear surface 1r, the active control elements are a plurality of heating / cooling elements, in particular the heating element 3. The heating elements 3 are actuated individually or in groups, and the control is effected by control means not shown. When one of the heating elements 3 is heated, the local section of the mounting surface 1o is heated by the material with very good heat conduction of the receiver, in particular metal. This results in local expansion of the wafer resting on the mounting surface 1o in this region. Thus, for a wafer which is held correspondingly in alignment on the receiving means and has a known position of twist / strain, it is possible to switch the wafer deformation, individual or several heating elements 3 Can be caused in a controlled manner, thus compensating for local twists. This also leads to an overall compensation of the overall twist, in particular due to a change in diameter in the X and / or Y direction of the wafer, especially due to a plurality of local compensations.

  A special advantage of the intervention of twisting on the wafer using this heating and / or cooling element is that this intervention can be achieved with minimal deformation, in particular deformation of the mounting surface and / or It can be achieved without deformation of the wafer in the vertical or Z direction. As a minimal deformation in this regard, the deformation of the support surface, in particular the deformation in the vertical direction of the wafer, ie in the right angle or Z direction, is less than 5 μm, preferably less than 2 μm, preferably less than 1 μm, particularly advantageous with respect to the mounting surface Is considered to be less than 0.5 μm.

  This is particularly advantageous for the production of interconnected pre-joins, for example pre-joins, which are based on van der Waals bonds. Based on the fact here that the mounting surface and in particular the wafer can be held flat, the bond waves that are conventionally performed in these pre-bonding steps can be affected in their propagation due to non-uniformities. Absent. Therefore, the risk of remaining unbonded portions (so-called voids) is greatly reduced. For the manufacture of these interconnect prebonds, as required by the present invention, <5 μm, advantageously <2 μm, preferably <1 μm and more preferably over the entire wafer surface. A uniformity of the mounting surface of <0.5 μm is desirable. These uniformity values are defined as the distance between the highest and lowest points in the portion of the mounting surface in contact with the wafer.

  The heating element 3 is advantageously evenly distributed below the mounting surface 1o. Advantageously, 10 or more heating elements 3 are present in the receiving means, in particular 50 or more heating elements 3, preferably 100 or more heating elements 3, more preferably 500 or more heating elements. These heating elements can be operated separately in the mounting surface and form areas that allow local action on the wafer. Advantageously, the individual areas of the mounting surface are thermally insulated from each other by suitable means. In particular, these regions are shaped to allow uniform and intimate placement of individual segments. Advantageously, the implementation of the segments as triangles, squares or hexagons is suitable for this purpose.

  In particular, a Peltier element is suitable as the heating element 3.

  In the second embodiment shown in FIGS. 2 a and 2 b, the heating element 3 is not shown and instead of the heating element 3 or in combination with the heating element 3, a piezo is mounted on the mounting surface 1 o. The element 4 is preferably present with a large distance from the mounting surface 1o to the back surface 1r.

  In this way, a controlled action on the mounting surface 1o is possible. The piezo element 4 can produce strain in the nanometer to micron range in operation.

  The piezo element 4 can correspond to the number of heating elements 3 described above, and a combination of the two embodiments can be envisaged as rights are required in the present invention.

  In a third embodiment of the invention shown in FIGS. 3a and 3b, the mounting is carried out in place of the heating element 3 and / or piezo element 4 and / or in combination with the heating element 3 and / or piezo element 4. There is a pin 5 with a particularly sharp pin end 5e that terminates on the surface 1o. At the initial position of the pin 5, the pin end 5e is flush with the mounting surface 1o. As long as there is a local twist of the wafer in the area of a given pin 5 as per the twist map or strain map information, the control means can move individual or several by moving the pin 5 or pin end 5e in the Z direction. By actuating the pins 5 in the direction of the wafer, it can act locally on the wafer. The pin end 5e thus exposes the wafer locally to a compressive force, which causes a local bulge or deflection of the wafer at this point. The pin 5 can be guided to slide as a whole through the guide opening 7 extending from the mounting surface 1o to the back surface 1r. Alternatively, only the pin end 5 e can be moved in the pin 5 and the pin 5 or the lower part of the pin can be fixed with respect to the guide opening 7. In this way, special sealing of the pin 5 can be ensured with respect to the internal space 1r.

  The number of pins 5 corresponds to the number of piezo elements 4 or heating elements 3, which can be combined here with one or more of the previous embodiments.

  In the embodiment shown in FIG. 4, the receiver 1 has a plurality of pressure chambers 6, which form a mounting surface 1o by a top wall 6o shown in FIG. 4b. The pressure chamber 6 extends through the internal space 1 i and is sealed against the internal space 1 i. Each of the pressure chambers 6 or the group of pressure chambers 6 can be separately pressurized, and can be controlled by the aforementioned control means. The pressure chamber 6 is provided such that at least its top wall 6o yields when pressure is applied, so that the top wall 6o is made thinner and / or more flexible than the other partition walls of the pressure chamber 6. . The opening 2 is connected to the internal space 1i.

  As is required in the present invention, only minimal deflection of the mounting surface 1o is caused by the aforementioned compression means 3, 4, 5, 6 by a maximum of 3 μm, in particular a maximum of 1 μm, preferably a maximum of 100 nm.

  In order to be able to combat local twisting by one or more of the previous embodiments, as described above, the control means determines where, how much and in what direction the twisting of the wafer occurs. I need to know. Only in this case is it possible to control or counteract and compensate for torsion. The strain map for each wafer generates information in the form of strain vectors, which are distributed over the wafer and are determined by the corresponding measuring means according to cited reference 2. Corresponding control data can be filed in the control unit and determined empirically, thus ensuring individual control for each wafer according to the wafer distortion map at the position indicated by the wafer position map. can do. Compensation can thus be performed automatically during wafer alignment.

  The active control elements 3, 4, 5, 6 are not shown to scale in the drawings and may have different sizes and shapes.

Embodiments of the present invention include the following aspects.
1. -Mounting surface (1o);
A mounting means for mounting a wafer on the mounting surface (1o);
-Active and locally controllable compensation means (3, 4, 5, 6) for at least partial compensation of the overall twist of the wafer;
Receiving means for receiving and mounting the wafer.
2. Receiving means according to item 1, characterized in that the temperature of the mounting surface (1o) can be locally influenced by the compensating means (3, 4, 5, 6).
3. 3. Receiving means according to item 1 or 2, characterized in that the distortion of the mounting surface (1o) can be influenced by the compensating means (3, 4, 5, 6).
4). The compensation means (3, 4, 5, 6) are piezo elements (4) arranged in a matrix, and the piezo elements (4) operate on the back surface (1r) of the mounting surface (1o). 4. The receiving means according to item 3, wherein the receiving means is capable of.
5. Receiving means according to item 4, characterized in that the piezo elements (4) can be actuated individually.
6). The shape of the mounting surface (1o) can be influenced in the direction perpendicular to the wafer by the compensation means (3, 4, 5, 6). The receiving means described in 1.
7). The shape of the mounting surface (1o) can be influenced in a direction perpendicular to the wafer by a mechanical action by the compensation means (3, 4, 5, 6). Receiving means.
8). Any of items 1 to 7, wherein the mounting surface (1o) can be exposed to pressure from the back surface (1r) of the mounting surface (1o) by the compensation means (3, 4, 5, 6). The receiving means according to claim 1.
9. Item 1 characterized in that the compensation means (3, 4, 5, 6) as a plurality of active control elements (3, 4, 5, 6) are integrated in the mounting surface (1o). The receiving means as described in any one of thru | or 8.
10. Item 9 is characterized in that the compensation means (3, 4, 5, 6) as a plurality of active control elements (3, 4, 5, 6) are embedded in the mounting surface (1o). Receiving means of description.
11. Item 9 or 10 characterized in that each of said active control elements (3, 4, 5, 6) or group of said active control elements (3, 4, 5, 6) can be actuated separately. The receiving means described in 1.
12 -Mounting surface (1o);
A mounting means for mounting a wafer on said mounting surface (1o);
Compensation means (3,4,5,6) controllable by temperature for at least partial active compensation of one or both of local and / or total twist of the wafer;
Receiving means for receiving and mounting the wafer.
13. 13. Receiving means according to item 12, characterized in that the temperature of the mounting surface (1o) can be locally influenced by the compensating means (3, 4, 5, 6).
14 14. Reception according to item 12 or 13, characterized in that one or both of a plurality of heating elements and a plurality of cooling elements are provided on the back surface (1r) of the mounting surface (1o) as an active control element. means.
15. 15. A receiving means according to item 14, wherein the heating element is a Peltier element.
16. A local alignment error caused by one or both of distortion and twisting of the first wafer relative to the second wafer when the first wafer is bonded to the second wafer; One or both of a first strain map of the second wafer and a second strain map of the second wafer and an evaluation by an evaluation means for evaluating one or both of the first and second strain maps. Means to determine,
-At least one receiving means according to any one of items 1 to 15 for receiving at least one of said wafers;
-One or both of a position map and a distortion map and simultaneous compensation by the compensation means, taking into account one or both of distortion and twist of the first wafer with respect to the second wafer, the alignment error; Alignment means for aligning the wafer with compensation based on the evaluation of
An apparatus for alignment of a first wafer with a second wafer.
17. -Detecting one or both of the first strain map of the first wafer and the second strain map of the second wafer and evaluating one or both of the first and second strain maps by the evaluation means; Determining a local alignment error;
Receiving at least one of the wafers on the receiving means according to any one of items 1 to 15;
-One or both of a position map and a distortion map and simultaneous compensation by the compensation means, taking into account one or both of distortion and twist of the first wafer with respect to the second wafer, the alignment error; Aligning the wafer with compensation based on the evaluation of:
For the alignment of the first wafer with the second wafer.
18. 18. The method according to item 17, wherein after the alignment, one or both of position maps and strain maps of one or both of the first and second wafers are detected.
19. The method according to item 18, wherein the detection is repeated after the alignment.

DESCRIPTION OF SYMBOLS 1 ... Receiver 1a ... Ring-shaped shoulder part 1i ... Internal space 1o ... Mounting surface 1w ... Perimeter wall 2 ... Opening part 3 ... Heating / cooling element 4 ... Piezo element 5 ... pin 5e ... pin end 6 ... pressure chamber 6a ... top wall 7 ... guide opening

Claims (10)

-Mounting surface (1o);
A mounting means for mounting a wafer on the mounting surface (1o);
-Compensation means (3, 4, 5, 6) for at least partial, active and in particular locally controllable compensation of the local and / or global twist of the wafer;
Receiving means for receiving and mounting the wafer, characterized in that   Receiving means according to claim 1, characterized in that the temperature of the mounting surface (1o) can be locally influenced by the compensating means (3, 4, 5, 6).   The distortion of the mounting surface (1o) can be influenced by the compensation means (3, 4, 5, 6), in particular by the arrangement of the piezo element (4), the piezo element (4) being 3. Mounting means according to claim 1 or 2, characterized in that it can preferably be actuated individually on the back surface (1r) of the surface (1o).   The shape of the mounting surface (1o) can be influenced in the Z direction by the compensation means (3, 4, 5, 6), in particular preferably by mechanical action. 4. The receiving means according to any one of 3.   The mounting surface (1o) is exposed to pressure from the back surface (1r) of the mounting surface (1o) by the compensation means (3, 4, 5, 6), in particular hydraulically and / or pneumatically. 5. Receiving means according to any one of claims 1 to 4, characterized in that   The compensation means (3, 4, 5, 6) as a plurality of active control elements (3, 4, 5, 6) are particularly integrated, preferably embedded, in the mounting means (1o). The receiving means according to any one of claims 1 to 5, wherein the receiving means is provided.   Receiving means according to claim 6, characterized in that each of the control elements (3, 4, 5, 6) or the group of control elements (3, 4, 5, 6) can be actuated separately. . A local alignment error caused by distortion and / or twisting of the first wafer relative to the second wafer when the first wafer is bonded to the second wafer; Means for determining by said first strain map and / or second strain map of said second wafer, and evaluation means for evaluation of said first and / or second strain map;
-At least one of the receiving means according to any one of claims 1 to 7 for receiving at least one of said wafers;
-A position map and / or the distortion map and an alignment means for wafer alignment taking into account the simultaneous guarantee by the compensation means;
An apparatus for alignment of a first wafer with a second wafer. Detecting a first strain map of the first wafer and / or a second strain map of the second wafer, and evaluating the first and / or second strain map by an evaluation means, Determining an alignment error;
Receiving at least one of the wafers on the receiving means according to claim 1;
-Aligning the wafer taking into account a position map and / or the distortion map and simultaneous compensation by means of compensation;
For the alignment of the first wafer with the second wafer.   10. Method according to claim 9, characterized in that, after the alignment, a single, particularly repeated detection of the position map and / or strain map of the first and second wafers is performed.

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